Device components with surface-embedded additives and related manufacturing methods

ABSTRACT

Active or functional additives are embedded into surfaces of host materials for use as components in a variety of electronic or optoelectronic devices, including solar devices, smart windows, displays, and so forth. Resulting surface-embedded device components provide improved performance, as well as cost benefits arising from their compositions and manufacturing processes.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.61/371,688, filed on Aug. 7, 2010, and U.S. Provisional Application No.61/446,926, filed on Feb. 25, 2011, the disclosures of which areincorporated herein by reference in their entireties.

FIELD OF THE INVENTION

The invention relates generally to structures with embedded additives.More particularly, the invention relates to device components withsurface-embedded additives to impart functionality such as electricalconductivity, thermal conductivity, spectral shifting, absorptionenhancement, and color change.

BACKGROUND

Functionalizing structures by incorporation of active or functionalparticles is an area of interest to a number of fields. One conventionaltechnique involves bulk incorporation, resulting in particles beingdispersed throughout bulk of base material. Bulk incorporation suffersfrom various deficiencies, including non-uniform mixing andagglomeration of particles within a base material and adverse impact onthe processability of the base material. Bulk incorporation is alsoinefficient if the goal is to expose particles at the surface, since anumber of particles remain dispersed within an interior of the basematerial. Another conventional technique involves coating processes.Coating processes also suffer from various deficiencies, includingnon-uniform mixing and agglomeration of particles within a coatingmaterial, poor adhesion, delamination, and high roughness.

It is against this background that a need arose to develop thesurface-embedded device components and related manufacturing methodsdescribed herein.

SUMMARY

Embodiments of the invention relate to active or functional additivesthat are embedded into embedding surfaces of host materials for use ascomponents in a variety of electronic or optoelectronic devices,including solar devices, smart windows, displays, touch sensor panels,touch displays, and so forth.

Embodiments of surface-embedded device components provide improvedperformance, as well as cost benefits arising from their composition andmanufacturing process. The device components can be manufactured by, forexample, a surface embedding process in which additives are physicallyembedded into a host material, while preserving desired characteristicsof the host material and imparting additional desired characteristics tothe resulting surface-embedded device components, such as electricalconductivity and spectral shifting.

Other aspects and embodiments of the invention are also contemplated.The foregoing summary and the following detailed description are notmeant to restrict the invention to any particular embodiment but aremerely meant to describe some embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the nature and objects of some embodimentsof the invention, reference should be made to the following detaileddescription taken in conjunction with the accompanying drawings.

FIG. 1A illustrates a device component in which additives are mixedthroughout a bulk of a device layer.

FIG. 1B illustrates a device component in which additives are mixedthroughout one device layer that is on top of another device layer.

FIG. 1C illustrates a device component in which additives aresuperficially or surface-deposited on top of a device layer.

FIG. 1D through FIG. 1I illustrate various surface-embedded devicecomponents implemented in accordance with embodiments of the invention.

FIG. 2A through FIG. 2H illustrate additional surface-embedded devicecomponents implemented in accordance with embodiments of the invention.

FIG. 3 illustrates the AM1.5-G solar spectrum at sea level as a functionof wavelength, according to an embodiment of the invention.

FIG. 4 is a logarithmic plot of resistance versus loading level ofadditives, according to an embodiment of the invention.

FIG. 5A through FIG. 5C illustrate manufacturing methods to formsurface-embedded device components, according to embodiments of theinvention.

FIG. 6 through FIG. 8 illustrate solar devices according to variousembodiments of the invention.

FIG. 9 illustrates a smart window according to an embodiment of theinvention.

FIG. 10 illustrates a display device according to an embodiment of theinvention.

FIG. 11 illustrates various configurations of additive concentrationsrelative to an embedding surface of a host material, according to anembodiment of the invention.

FIG. 12 are schematics of a number of electronic device architecturesrepresenting different types of touch sensors and displays according toan embodiment of the invention.

DETAILED DESCRIPTION Definitions

The following definitions apply to some of the aspects described withregard to some embodiments of the invention. These definitions maylikewise be expanded upon herein.

As used herein, the singular terms “a,” “an,” and “the” include pluralreferents unless the context clearly dictates otherwise. Thus, forexample, reference to an object can include multiple objects unless thecontext clearly dictates otherwise.

As used herein, the term “set” refers to a collection of one or moreobjects. Thus, for example, a set of objects can include a single objector multiple objects. Objects of a set can also be referred to as membersof the set. Objects of a set can be the same or different. In someinstances, objects of a set can share one or more commoncharacteristics.

As used herein, the term “adjacent” refers to being near or adjoining.Adjacent objects can be spaced apart from one another or can be inactual or direct contact with one another. In some instances, adjacentobjects can be connected to one another or can be formed integrally withone another.

As used herein, the terms “connect,” “connected,” and “connection” referto an operational coupling or linking. Connected objects can be directlycoupled to one another or can be indirectly coupled to one another, suchas via another set of objects.

As used herein, the terms “substantially” and “substantial” refer to aconsiderable degree or extent. When used in conjunction with an event orcircumstance, the terms can refer to instances in which the event orcircumstance occurs precisely as well as instances in which the event orcircumstance occurs to a close approximation, such as accounting fortypical tolerance levels of the manufacturing methods described herein.

As used herein, the terms “optional” and “optionally” mean that thesubsequently described event or circumstance may or may not occur andthat the description includes instances where the event or circumstanceoccurs and instances in which it does not.

As used herein, relative terms, such as “inner,” “interior,” “outer,”“exterior,” “top,” “bottom,” “front,” “rear,” “back,” “upper,”“upwardly,” “lower,” “downwardly,” “vertical,” “vertically,” “lateral,”“laterally,” “above,” and “below,” refer to an orientation of a set ofobjects with respect to one another, such as in accordance with thedrawings, but do not require a particular orientation of those objectsduring manufacturing or use.

As used herein, the term “sub-nanometer range” or “sub-nm range” refersto a range of dimensions less than about 1 nanometer (“nm”), such asfrom about 0.1 nm to about 1 nm.

As used herein, the term “nanometer range” or “nm range” refers to arange of dimensions from about 1 nm to about 1 micrometer (“μm”). The nmrange includes the “lower nm range,” which refers to a range ofdimensions from about 1 nm to about 10 nm, the “middle nm range,” whichrefers to a range of dimensions from about 10 nm to about 100 nm, andthe “upper nm range,” which refers to a range of dimensions from about100 nm to about 1 μm.

As used herein, the term “micrometer range” or “μm range” refers to arange of dimensions from about 1 μm to about 1 millimeter (“mm”). The μmrange includes the “lower μm range,” which refers to a range ofdimensions from about 1 μm to about 10 μm, the “middle μm range,” whichrefers to a range of dimensions from about 10 μm to about 100 μm, andthe “upper μm range,” which refers to a range of dimensions from about100 μm to about 1 mm.

As used herein, the term “aspect ratio” refers to a ratio of a largestdimension or extent of an object and an average of remaining dimensionsor extents of the object, where the remaining dimensions are orthogonalwith respect to one another and with respect to the largest dimension.In some instances, remaining dimensions of an object can besubstantially the same, and an average of the remaining dimensions cansubstantially correspond to either of the remaining dimensions. Forexample, an aspect ratio of a cylinder refers to a ratio of a length ofthe cylinder and a cross-sectional diameter of the cylinder. As anotherexample, an aspect ratio of a spheroid refers to a ratio of a major axisof the spheroid and a minor axis of the spheroid.

As used herein, the term “sub-nano-sized additive” refers to an additivethat has at least one dimension in the sub-nm range. A sub-nano-sizedadditive can have any of a wide variety of shapes, and can be formed ofa wide variety of materials.

As used herein, the term “nano-sized additive” refers to an additivethat has at least one dimension in the nm range. A nano-sized additivecan have any of a wide variety of shapes, and can be formed of a widevariety of materials. Examples of nano-sized additives includenanowires, nanotubes, nanoplatelets, and nanoparticles.

As used herein, the term “nanowire” refers to an elongated, nano-sizedadditive that is substantially solid. Typically, a nanowire has alateral dimension (e.g., a cross-sectional dimension in the form of awidth, a diameter, or a width or diameter that represents an averageacross orthogonal directions) in the nm range, a longitudinal dimension(e.g., a length) in the μm range, and an aspect ratio that is about 3 orgreater.

As used herein, the term “nanoplatelet” refers to a planar-likenano-sized additive that is substantially solid.

As used herein, the term “nanotube” refers to an elongated, hollow,nano-sized additive. Typically, a nanotube has a lateral dimension(e.g., a cross-sectional dimension in the form of a width, an outerdiameter, or a width or outer diameter that represents an average acrossorthogonal directions) in the nm range, a longitudinal dimension (e.g.,a length) in the μm range, and an aspect ratio that is about 3 orgreater.

As used herein, the term “nanoparticle” refers to a spheroidal,nano-sized additive. Typically, each dimension (e.g., a cross-sectionaldimension in the form of a width, a diameter, or a width or diameterthat represents an average across orthogonal directions) of ananoparticle is in the nm range, and the nanoparticle has an aspectratio that is less than about 3, such as about 1.

As used herein, the term “micron-sized additive” refers to an additivethat has at least one dimension in the μm range. Typically, eachdimension of a micron-sized additive is in the μm range or beyond the μmrange. A micron-sized additive can have any of a wide variety of shapes,and can be formed of a wide variety of materials. Examples ofmicron-sized additives include microwires, microtubes, andmicroparticles.

As used herein, the term “microwire” refers to an elongated,micron-sized additive that is substantially solid. Typically, amicrowire has a lateral dimension (e.g., a cross-sectional dimension inthe form of a width, a diameter, or a width or diameter that representsan average across orthogonal directions) in the μm range and an aspectratio that is about 3 or greater.

As used herein, the term “microtube” refers to an elongated, hollow,micron-sized additive. Typically, a microtube has a lateral dimension(e.g., a cross-sectional dimension in the form of a width, an outerdiameter, or a width or outer diameter that represents an average acrossorthogonal directions) in the μm range and an aspect ratio that is about3 or greater.

As used herein, the term “microparticle” refers to a spheroidal,micron-sized additive. Typically, each dimension (e.g., across-sectional dimension in the form of a width, a diameter, or a widthor diameter that represents an average across orthogonal directions) ofa microparticle is in the μm range, and the microparticle has an aspectratio that is less than about 3, such as about 1.

As used herein, the term “ultraviolet range” refers to a range ofwavelengths from about 5 nm to about 400 nm.

As used herein, the term “visible range” refers to a range ofwavelengths from about 400 nm to about 700 nm.

As used herein, the term “infrared range” refers to a range ofwavelengths from about 700 nm to about 2 mm.

As used herein, the term “encapsulant” refers to a pottant or pottingmaterial, a front sheet, an interlayer, an optically clear adhesive (orOCA), and/or a back sheet material used for encapsulating or sealing anelectronic device to be a barrier from the environment and/or as anoptical bonding material. In some instances, an encapsulant can bothserve as an encapsulating material and a front sheet. In some instances,an encapsulant may include one or more of the following materials:ethylene vinyl acetate (or EVA), polyvinyl butyral (or PVB), au ionomer,thermoplastic polyurethane (or TPU), thermoplastic polyolefin (or TPO),thermoplastic elastomer (or TPE), silicone, siloxane, any other polymer,diamond-like carbon thin films, sol-gel, sodium silicate, andencapsulants available as Teonex® PEN, Teflon®, Melinex® ST, Elvax® PVEVA, DuPont PV5200 Encapsulant, DuPont PV5300 Encapsulant, Dow CorningPV-6100 Encapsulant, 1-2577 Low VOC coating, 1-2620 Low VOC Coating,PV-6150 cell encapsulant, PV Potting agents, PV sealants, Dow Enlightpolyolefin encapsulant films, STR EVA Photocap® A9918P/UF, STR Photocap25539P thermoplastic encapsulant, STR Laminates, Solutia Vistasolar EVA,Etimex Solar GmbH encapsulants, Saflex PVB, Salfex PG41 thin gaugeencapsulant, Cytec encapsulants, DuPont PV5400 ionomer encapsulantsheet, Ellsworth epoxy encapsulants, V-gool EVA encapsulant, BixbyBixCure EVA, Saint-Gobain LightSwitch Frontsheet Complete, Saint-GobainLightSwitch encapsulant, 3M 8171, 3M 8172, or any combination orvariation of standard encapsulant, front sheet, or back sheet materials.

Device Components with Surface-Embedded Additives

The surface-embedded device components described herein differ fromother possible approaches that seek to attain desired characteristicsthrough incorporation of active or functional additives. Three otherapproaches are illustrated in FIG. 1A through FIG. 1C and are contrastedwith improved, surface-embedded device components illustrated anddescribed with reference to FIG. 1D through FIG. 1I and FIG. 2A throughFIG. 2H.

FIG. 1A illustrates a device component 100 in which additives 102 aremixed throughout a bulk of a device layer 104. FIG. 1B illustrates adevice component 106 in which additives 108 are mixed throughout onedevice layer 110, which (along with the additives 108) is coated orotherwise disposed on top of another device layer 112. FIG. 1Cillustrates a device component 114 in which additives 116 aresuperficially or surface-deposited on top of a device layer 118. Aconfiguration such as depicted in FIG. 1C can have poor adhesion of thesurface-deposited additives 116 to the device layer 118.

In contrast, FIG. 1D through FIG. 1I illustrate various surface-embeddeddevice components 120, 122, 124, 126, 128, and 170 implemented inaccordance with embodiments of the invention. FIG. 1D is a schematic ofsurface-embedded additives 130 that are partially exposed and partiallyburied into a top, embedding surface 134 of a host material 132, whichcorresponds to a device layer or other component of an electronic oroptoelectronic device. The embedding surface 134 also can be a bottomsurface of the host material 132. As illustrated in FIG. 1D, theadditives 130 are localized adjacent to the embedding surface 134 andwithin an embedding region 138 of the host material 132, with aremainder of the host material 132 largely devoid of the additives 130.In the illustrated embodiment, the embedding region 138 is relativelythin (e.g., having a thickness less than or much less than an overallthickness of the host material 132, or having a thickness comparable toa characteristic dimension of the additives 130), and, therefore, can bereferred to as “planar” or “planar-like.” Through proper selection ofthe host material 132, such as certain polymers or polymer-containingcomposite materials, the device component 120 can be transparent andflexible, as well as lightweight. However, other embodiments can beimplemented in which the device component 120 need not be transparent orflexible. The device component 120 (as well as other surface-embeddedstructures described herein) can be much smoother than conventionalstructures. High smoothness (e.g., low roughness) can be desirablebecause roughness can lead to penetration into adjacent device layers,poor adhesion to adjacent device layers, delamination, and otherundesirable effects.

FIG. 1E is a schematic of surface-embedded additives 136 that are fullyembedded into a top, embedding surface 140 of a host material 142, whichcorresponds to a device layer or other component of an electronic oroptoelectronic device. The embedding surface 140 also can be a bottomsurface of the host material 142. As illustrated in FIG. 1E, theadditives 136 are localized adjacent to the embedding surface 140 andwithin an embedding region 144 of the host material 142, with aremainder of the host material 142 largely devoid of the additives 136.In the illustrated embodiment, the embedding region 144 is relativelythin having a thickness less than or much less than an overall thicknessof the host material 142, or having a thickness comparable to acharacteristic dimension of the additives 136), and, therefore, can bereferred to as “planar” or “planar-like.” In such manner, the additives136 can remain in a substantially planar configuration, despite beingfully embedded underneath the embedding surface 140 by a certainrelatively uniform distance. Through proper selection of the hostmaterial 142, such as certain polymers or polymer-containing compositematerials, the device component 122 can be transparent and flexible, aswell as lightweight. However, other embodiments can be implemented inwhich the device component 122 need not be transparent or flexible. FIG.1I is a schematic similar to FIG. 1E, but with additives 172 fullyembedded and close to (or just underneath) a top, embedding surface 176of a host material 174.

FIG. 1F is a schematic of surface-embedded additives 146 that are fullyembedded into a top, embedding surface 148 of a host material 150, whichcorresponds to a device layer or other component of an electronic oroptoelectronic device. The embedding surface 148 also can be a bottomsurface of the host material 150. As illustrated in FIG. 1F, theadditives 146 are localized adjacent to the embedding surface 148 andwithin an embedding region 152 of the host material 150, with aremainder of the host material 150 largely devoid of the additives 146.In the illustrated embodiment, a thickness of the embedding region 152is greater than a characteristic dimension of the additives 146 (e.g., across-sectional diameter of an individual one of the additives 146 or anaverage cross-sectional diameter across the additives 146), but stillless than (or much less than) an overall thickness of the host material150. The additives 146 can be distributed or arranged within theembedding region 152 as multiple layers, with the additives 146 of aparticular layer remaining in a substantially planar configuration,despite being fully embedded underneath the embedding surface 148. Notethat, although not illustrated in FIG. 1F, another implementation wouldbe similar to FIG. 1F, but with the additives 146 partially exposed atthe embedding surface 148 of the host material 150.

FIG. 1G is a schematic of surface-embedded additives 154 that arepartially exposed and partially buried into a top, embedding surface 156of a host material 158, which corresponds to one device layer that iscoated or otherwise disposed on top of another device layer 160. Thehost material 158 can be implemented as a coating or other secondarymaterial, such as a slurry or a paste, that is disposed on top of thedevice layer 160 serving as a substrate. As illustrated in FIG. 1G, theadditives 154 are localized adjacent to the embedding surface 156 andwithin an embedding region 162 of the host material 158, with aremainder of the host material 158 largely devoid of the additives 154.It is also contemplated that the additives 154 can be distributedthroughout a larger volume fraction within the host material 158, suchas in the case of a relatively thin coating having a thicknesscomparable to a characteristic dimension of the additives 154. In theillustrated embodiment, the embedding region 162 is relatively thin,and, therefore, can be referred to as “planar” or “planar-like,” Notethat, although not illustrated in FIG. 1G, another implementation wouldbe similar to FIG. 1G, but with the additives 154 fully embedded belowthe embedding surface 156 of the host material 158.

FIG. 1H is a schematic of surface-embedded additives 164 that arelocalized across a host material 166 so as to form an ordered pattern.The additives 164 can be partially embedded into a top, embeddingsurface 168 and localized within an embedding region of the hostmaterial 166 (e.g., similar to FIG. 1D and FIG. 1G), fully embeddedbelow the embedding surface 168 (e.g., similar to FIG. 1E, FIG. 1I, andFIG. 1F), or a combination thereof, but the additives 164 are notlocated uniformly across the host material 166 but rather are patterned.Note that, although a grid pattern is illustrated in FIG. 1H, patterns,in general, can include aperiodic (or non-periodic, random) patterns aswell as periodic patterns, such as diamond patterns, square patterns,rectangular patterns, triangular patterns, various polygonal patterns,wavy patterns, angular patterns, interconnect patterns (e.g., in theform circuitry in electronic or optoelectronic devices), or anycombination thereof. FIG. 1H illustrates that, although the formation ofa pattern occurs, a zoomed up view of a “line” section of the patternreveals that the configuration of the individual “line” section includessurface-embedded additives similar to any, or a combination, of theconfigurations illustrated in FIG. 1D through FIG. 1G, FIG. 1I, and FIG.2 below. To provide desired characteristics such as electricalconductivity, thermal conductivity, and absorption enhancement, theadditives 164 (as well as the additives illustrated in FIG. 1D throughFIG. 1G, FIG. 1I, and FIG. 2 below) can include metallic nanowires, suchas silver (or Ag) nanowires, copper (or Cu) nanowires, or a combinationthereof, with a longitudinal dimension that is, on average, shorter thana characteristic length of the pattern (e.g., a length of an individual“line” section), a longitudinal dimension that is, on average, longerthan a characteristic width of the pattern (e.g., a width of anindividual “line” section), or both. Other types of additives and othercombinations of additives also can be used in place of, or incombination with, metallic nanowires, such as nanoparticles includingsilver nanoparticles or other metallic nanoparticles. In someembodiments, the additives 164 can be sintered or otherwise fused toform solid lines, which can serve as interconnects or interconnectiongrids for use in devices such as solar devices, touch sensors, and smartwindows. Such embodiments provide a number of advantages overconventional approaches, including enhanced durability and allowing theomission of a coating or other binding material that can be prone todelamination and that can inhibit conductivity or increase resistance.

Other configurations of surface-embedded device components areillustrated in FIG. 2A through FIG. 2H. Certain aspects of thesurface-embedded device components illustrated in FIG. 2A through FIG.2H can be implemented in a similar fashion as illustrated and describedabove in FIG. 1D through FIG. 1I, and those aspects are not repeatedbelow.

FIG. 2A is a schematic of surface-embedded additives that include atleast two different types of additives 200 and 202 in the form ofdifferent types of nanowires, different types of nanotubes, or acombination thereof. In general, the additives 200 and 202 can differ,for example, in terms of their dimensions, shapes, material composition,or a combination thereof. As illustrated in FIG. 2A, the additives 200and 202 are localized within an embedding region 204 in a particulararrangement, such as in a layered arrangement. Each layer can primarilyinclude a respective, different type of additive, although additives ofdifferent types also can cross between layers. Such a layeredarrangement of the additives 200 and 202 also can be described in termsof different embedding regions, with each different type of additivebeing localized within a respective embedding region. Although theadditives 200 and 202 are illustrated as fully embedded, it iscontemplated that at least some of the additives 200 and 202 can bepartially embedded and surface-exposed. FIG. 2B is a schematic similarto FIG. 2A, but with at least two different types of additives 206 and208 in the form of different types of nanoparticles. It is alsocontemplated that nanoparticles can be included in combination witheither, or both, nanowires and nanotubes. It is further contemplatedthat other embodiments described herein in terms of a particular type ofadditive can be implemented with different types of additives. Althoughthe additives 206 and 208 are illustrated as fully embedded, it iscontemplated that at least some of the additives 206 and 208 can bepartially embedded and surface-exposed.

FIG. 2C is a schematic of surface-embedded additives 210 that arepartially embedded into a host material 212, which corresponds to onedevice layer, and where another device layer 214 implemented as acoating fills in around the additives 210, either fully covering theadditives 210 or leaving them partially exposed as illustrated in FIG.2C. The device layer 214 can have the same or a similar composition asthe host material 212 (or other host materials described herein), or canhave a different composition to provide additional or modifiedfunctionality, such as when implemented using an electrically conductivematerial or semiconductor (e.g., indium tin oxide (“ITO”), ZnO(i),ZnO:Al, ZnO:B, SnO₂:F, Cd₂SnO₄, CdS, ZnS, another doped metal oxide, anelectrically conductive or semiconducting polymer, a fullerene-basedcoating, such as carbon nanotube-based coating, or another electricallyconductive material that is transparent) to serve as a buffer layer toadjust a work function in the context of solar devices or to provide aconductive path for the flow of an electric current, in place of, or incombination with, a conductive path provided by the surface-embeddedadditives 210. In the case of ITO, for example, the presence of thesurface-embedded additives 210 can provide cost savings by allowing areduced amount of ITO to be used and, therefore, a reduced thickness ofthe device layer 214 (relative to the absence of the additives 210),such as a thickness less than about 100 nm, no greater than about 75 nm,no greater than about 50 nm, no greater than about 40 nm, no greaterthan about 30 nm, no greater than about 20 nm, or no greater than about10 nm, and down to about 5 nm or less. Additionally, the presence of thesurface-embedded additives 210 can allow for solution deposition of ITO(instead of sputtering) with a low temperature cure. The resulting,relatively low conductivity ITO layer can still satisfy work functionmatching, while the additives 210 can mitigate the reduced conductivityexhibited by solution-deposited ITO without high temperature cure. It iscontemplated that the additives 210 can be arranged in a pattern (e.g.,a grid pattern or any other pattern such as noted above for FIG. 1H),and the device layer 214 can be formed with a substantially matchingpattern (e.g., a matching grid pattern or any other matching patternsuch as noted above for FIG. 1H) so as to either fully cover theadditives 210 or leaving them partially exposed. Alternatively, or inconjunction, a network of the additives 210 can be supplemented by aregular conductive grid that is deposited or otherwise applied.

The surface-embedded device component illustrated in FIG. 2C can also beuseful, for example, as a touch sensor panel, a touch sensor, or a touchdisplay, where the additives 210 can form a projected capacitive touchsensor, a capacitive touch sensor, a resistive touch sensor, or acombination thereof. In certain embodiments, the host material 212 is,for example, an optically clear adhesive (or OCA). In certainembodiments, the additives 210 can serve as a transparent conductingelectrode that is patterned, unpatterned, or a combination thereof. Suchimplementations helps to, inter alia, reduce the number of layersincluded in a touch sensor.

FIG. 2D is a schematic similar to FIG. 1D, but with nanoparticles 216surface-embedded in combination with nanowires 218 (or other high aspectratio additives) and localized within a “planar” or “planar-like”embedding region 222. Although not illustrated, either, or both, of thenanoparticles 216 and the nanowires 218 can be fully below a top,embedding surface 220 (e.g., similar to the configuration illustrated inFIG. 1E, FIG. 1F, or FIG. 1I).

FIG. 2E is a schematic similar to FIG. 1D, but with at least twodifferent types of additives 224 and 226 in the form of different typesof nanowires, different types of nanotubes, or a combination ofnanowires and nanotubes. Although not illustrated, either, or both, ofthe different types of additives 224 and 226 can be fully below a top,embedding surface 228 (e.g., similar to the configuration illustrated inFIG. 1E, FIG. 1F, or FIG. 1I).

FIG. 2F is a schematic of a host material 230, where the host material230 is embedded with additives on either side of the host material 230.In particular, additives 232 are at least partially embedded into a top,embedding surface 236 of the host material 230 and localized adjacent tothe top, embedding surface 236 and within an embedding region 240 of thehost material 230, while additives 234 are at least partially embeddedinto a bottom, embedding surface 238 of the host material 230 andlocalized adjacent to the bottom, embedding surface 238 and within anembedding region 242 of the host material 230. It is contemplated that,for any particular side of the host material 230, the extent ofembedding of additives in the host material 230 or the inclusion ofdifferent types of additives can be implemented in a similar fashion asdescribed above and subsequently below. Although the additives 232 and234 are illustrated as partially embedded into the host material 230, itis contemplated that at least some of the additives 232 and 234 can befully embedded into the host material 230. It is further contemplatedthat additives can be embedded into additional surfaces of the hostmaterial 230, such as any one or more of the edges or lateral surfacesof the host material 230.

The surface-embedded device component illustrated in FIG. 2F can beuseful, for example, as an encapsulant layer of a solar device, wherethe additives 232 face incident sunlight and perform spectral shiftingto match a bandgap energy of a photoactive layer of the solar device,and the additives 234 serve as an electrode or current collector andinclude electrically conductive materials, such as carbon, a metal, ametal oxide, carbon black, graphene, or a combination thereof, in theform of nanoparticles, microparticles, nanowires, microwires, nanotube,microtubes, or other forms or a combination of such forms. Thesurface-embedded device component illustrated in FIG. 2F also can beuseful, for example, as an encapsulant layer or other device layer whereit is desirable to space apart the additives 232 and 234, such as in thecase of incompatible phosphors.

The surface-embedded device component illustrated in FIG. 2F can also beuseful, for example, as a touch sensor panel, a touch sensor, or a touchdisplay, where the additives 232 and 234 can interact to form aprojected capacitive touch sensor, a capacitive touch sensor, aresistive touch sensor, or a combination thereof. In certainembodiments, the host material 230 is, for example, an optically clearadhesive (or OCA). In certain embodiments, the additives 232 and 234 canserve as transparent conducting electrodes that are patterned,unpatterned, or a combination thereof. Such implementations helps to,inter alia, reduce the number of layers included in a touch sensor.

FIG. 2G is a schematic similar to FIG. 2C, but with surface-embeddedadditives 244 that are partially embedded into a host material 246,which corresponds to a device layer implemented as a coating disposed ontop of another device layer 248, and where another device layer 250implemented as a coating fills in at least one layer around theadditives 244 and is electrically connected to the additives 244, eitherleaving them partially exposed or fully covering the additives 244 asillustrated in FIG. 2G. By fully covering the additives 244, theresulting surface of the device layer 250 is quite smooth (e.g., havinga smoothness or a roughness substantially comparable to that of aninherent smoothness or roughness of the device layer 250 in the absenceof the additives 244). The device layer 250 can have the same or asimilar composition as the host material 246 (or other host materialsdescribed herein), or can have a different composition to provideadditional or modified functionality, such as when implemented using anelectrically conductive material or semiconductor (e.g., ITO, ZnO(i),ZnO:Al, ZnO:B, SnO₂:F, Cd₂SnO₄, CdS, ZnS, another doped metal oxide, anelectrically conductive or semiconducting polymer, a fullerene-basedcoating, such as carbon nanotube-based coating, or another electricallyconductive material that is transparent) to serve as a buffer layer toadjust a work function in the context of solar devices or to provide aconductive path for the flow of an electric current, in place of, or incombination with, a conductive path provided by the surface-embeddedadditives 244. In the case of ITO, for example, the presence of thesurface-embedded additives 244 can provide cost savings by allowing areduced amount of ITO to be used and, therefore, a reduced thickness ofthe device layer 250 (relative to the absence of the additives 244),such as a thickness less than about 100 nm, no greater than about 75 nm,no greater than about 50 nm, no greater than about 40 nm, no greaterthan about 30 nm, no greater than about 20 nm, or no greater than about10 nm, and down to about 5 nm or less. Additionally, the presence of thesurface-embedded additives 244 can allow for solution deposition of no(instead of sputtering) with a low temperature cure. The resulting,relatively low conductivity ITO layer can still satisfy work functionmatching, while the additives 244 can mitigate the reduced conductivityexhibited by solution-deposited ITO without high temperature cure. It iscontemplated that the additives 244 can be arranged in a pattern (e.g.,a grid pattern or any other pattern such as noted above for FIG. 1H),and the device layer 250 can be formed with a substantially matchingpattern (e.g., a matching grid pattern or any other matching patternsuch as noted above for FIG. 1H) so as to either fully cover theadditives 244 or leaving them partially exposed. Alternatively, or inconjunction, a network of the additives 244 can be supplemented by aregular conductive grid that is deposited or otherwise applied.

FIG. 2H is a schematic similar to FIG. 2F, with additives 260 that areat least partially embedded into a top, embedding surface 264 of a hostmaterial 262 and localized adjacent to the top, embedding surface 264and within an embedding region 266 of the host material 262, and withadditives 272 that are at least partially embedded into a bottom,embedding surface 268 of the host material 262 and localized adjacent tothe bottom, embedding surface 268 and within an embedding region 270 ofthe host material 262. Although the additives 260 and 272 areillustrated as fully embedded into the host material 262, it iscontemplated that at least some of the additives 260 and 272 can bepartially embedded and surface-exposed. In the illustrated embodiment,the host material 262 is also embedded with additives 274 disposedbetween the additives 260 and 272 and localized within an embeddingregion 276 of an interior of the host material 262. The surface-embeddeddevice component illustrated in FIG. 2H can be useful, for example, fora smart window, where the additives 260 and 272 serve as a pair ofelectrodes, and the additives 274 provide a color or shade changefunctionality.

One aspect of certain surface-embedded device components describedherein is the provision of a vertical additive concentration gradient ina host material, namely a gradient along a thickness direction of thehost material. Bulk incorporation (e.g., as illustrated in FIG. 1A) aimsto provide an uniform vertical additive concentration gradientthroughout a host material, although agglomeration and other effects mayprevent such uniform gradient to be achieved in practice. For aconventional coating implementation (e.g., as illustrated in FIG. 1B), avertical additive concentration gradient can exist as between a coatingand an underlying substrate; however, and similar to bulk incorporation,a conventional coating implementation aims to provide an uniformvertical additive concentration gradient throughout the coating. Incontrast, the surface-embedded device components described herein allowfor variable, controllable vertical additive concentration gradient, inaccordance with a localization of additives within an embedding regionof a host material. For certain implementations, the extent oflocalization of additives within an embedding region is such that atleast a majority (by weight, volume, or number density) of the additivesare included within the embedding region, such as at least about 60% (byweight, volume, or number density) of the additives are so included, atleast about 70% (by weight, volume, or number density) of the additivesare an included, at least about 80% (by weight, volume, or numberdensity) of the additives are on included, at least about 90% (byweight, volume, or number density) of the additives are so included, orat least about 95% (by weight, volume, or number density) of theadditives are an included. For example, substantially all of theadditives can be localized within the embedding region, such that aremainder of the host material is substantially devoid of the additives.For certain applications and certain device components, it is alsocontemplated that bulk incorporation or a conventional coatingimplementation can be used in place of or in combination with,localization of additives within an embedding region.

In general, additives can include an electrically conductive material, asemiconductor, a phosphor, a multichromic material, another type ofmaterial, or a combination thereof which can be in the form ofnano-sized additives, micron-sized additives, as well as additives sizedin the sub-nm range, Additives also can be in the form of colloids andatomic or molecular species, such as dissolved atomic or molecularspecies. For example, at least one additive can have a cross-sectionaldimension (or a population of additives can have an averagecross-sectional dimension) in the range of about 0.1 nm to about 1 mm.In some embodiments, the cross-sectional dimension (or the averagecross-sectional dimension) is in the range of about 1 nm to about 100nm, about 1 nm to about 20 nm, about 20 nm to about 100 nm, about 1 nmto about 50 microns, about 100 nm to about 1 micron, about 1 nm to about100 microns, or about 500 nm to about 50 microns. In some embodiments,substantially all additives have a cross-sectional dimension in therange of about 0.1 nm to about 1 mm or about 0.1 nm to about 100microns.

In cases where it is desirable to impart electrical conductivity,additives can include an electrically conductive material, asemiconductor, or a combination thereof. Examples of electricallyconductive materials include metals (e.g., silver, copper, and gold),metal alloys, silver nanowires, copper nanowires, gold nanowires,carbon-based conductors (e.g., carbon nanotubes, graphene, andbuckyballs), metal oxides and chaicogenides that are optionally doped(e.g., ITO, ZnO(i), ZnO:Al, ZnO:B, SnO₂:F, Cd₂SnO₄, CdS, ZnS, and otherdoped metal oxides), electrically conductive polymers, and anycombination thereof. Examples of semiconductor materials includesemiconducting polymers, Group IVB elements (e.g., carbon (or C),silicon (or Si), and germanium (or Ge)), Group IVB-IVB binary alloys(e.g., silicon carbide (or SiC) and silicon germanium (or SiGe)), GroupIIB-VIB binary alloys (e.g., cadmium selenide (or CdSe), cadmium sulfide(or CdS), cadmum telluride (or CdTe), zinc oxide (or ZnO), zinc selenide(or ZnSe), zinc telluride (or ZnTe), and zinc sulfide (or ZnS)), GroupIIB-VIB ternary alloys (e.g., cadmium zinc telluride (or CdZrTe),mercury cadmium telluride (or HgCdTe), mercury zinc telluride (orHgZnTe), and mercury zinc selenide (or HgZnSe)), Group IIIB-VB binaryalloys (e.g., aluminum antimonide (or AlSb), aluminum arsenide (orAlAs), aluminium nitride (or AlN), aluminium phosphide (or AlP), boronnitride (or BN), boron phosphide (or BP), boron arsenide (or BAs),gallium antimonide (or GaSb), gallium arsenide (or GaAs), galliumnitride (or GaN), gallium phosphide (or GaP), indium antimonide (orInSb), indium arsenide (or InAs), indium nitride (or InN), and indiumphosphide (or InP)), Group IIIB-VB ternary alloys (e.g., aluminiumgallium arsenide (or AlGaAs or Al_(x)Ga_(1-x)As), indium galliumarsenide (or InGaAs or In_(x)Ga_(1-x)As), indium gallium phosphide (orInGaP), aluminium indium arsenide (or AlInAs), aluminium indiumantimonide (or AlInSb), gallium arsenide nitride (or GaAsN), galliumarsenide phosphide (or GaAsP), aluminium gallium nitride (or AlGaN),aluminium gallium phosphide (or AlGaP), indium gallium nitride (orInGaN), indium arsenide antimonide (or InAsSb), and indium galliumantimonide (or InGaSb)), Group IIIB-VB quaternary alloys (e.g.,aluminium gallium indium phosphide (or AlGaInP), aluminium galliumarsenide phosphide (or AlGaAsP), indium gallium arsenide phosphide (orInGaAsP), aluminium indium arsenide phosphide (or AlInAsP), aluminiumgallium arsenide nitride (or AlGaAsN), indium gallium arsenide nitride(or InGaAsN), indium aluminium arsenide nitride (or InAlAsN), andgallium arsenide antimonide nitride (or GaAsSbN)), and Group IIIB-VBquinary alloys (e.g., gallium indium nitride arsenide antimonide (orGaInNAsSb) and gallium indium arsenide antimonide phosphide (orGaInAsSbP)), Group IB-VIIB binary alloys (e.g., cupruous chloride (orCuCl)), Group IVB-VIB binary alloys (e.g., lead selenide (or PbSe), leadsulfide (or PbS), lead telluride (or PbTe), tin sulfide (or SnS), andtin telluride (or SrTe)), Group IVB-VIB ternary alloys (e.g., lead tintelluride (or PbSnTe), thallium tin telluride (or Tl₂SnTe₅), andthallium germanium telluride (or Tl₂GeTe₅)), Group VB-VIB binary alloys(e.g., bismith telluride (or Bi₂Te₃)), Group IIB-VB binary alloys (e.g.,cadmium phosphide (or Cd₃P₂), cadmium arsenide (or Cd_(s)As₂), cadmiumantimonide (or Cd₃Sb₂), zinc phosphide (or Zn₃P₂), zinc arsenide (orZn₃As₂), and zinc antimonide (or Zn₃Sb₂)), and other binary, ternary,quaternary, or higher order alloys of Group IB (or Group 11) elements,Group IIB (or Group 12) elements, Group IIIB (or Group 13) elements,Group IVB (or Group 14) elements, Group VB (or Group 15) elements, GroupVIB (or Group 16) elements, and Group VIIB (or Group 17) elements, suchas copper indium gallium selenide (or CIGS), as well as any combinationthereof.

Additives can include, for example, nanoparticles, nanowires, nanotubes(e.g., multi-walled nanotubes (“MWNTs”), single-walled nanotubes(“SWNTs”), double-walled nanotubes (“DWNTs”), graphitized or modifiednanotubes), fullerenes, buckyballs, graphene, microparticles,microwires, microtubes, core-shell nanoparticles or microparticles,core-multishell nanoparticles or microparticles, core-shell nanowires,and other additives having shapes that are substantially tubular, cubic,spherical, or pyramidal, and characterized as amorphous, crystalline,tetragonal, hexagonal, trigonal, orthorhombic, monoclinic, or triclinic,or any combination thereof.

Examples of core-shell nanoparticles and core-shell nanowires includethose with a ferromagnetic core (e.g., iron, cobalt, nickel, manganese,as well as their oxides and alloys formed with one or more of theseelements), with a shell formed of a metal, a metal alloy, a metal oxide,carbon, or any combination thereof (e.g., silver, copper, gold,platinum, ZnO, ZnO(i), ZnO:Al, ZnO:B, SnO₂:F, Cd₂SnO₄, CdS, ZnS, TiO₂,ITO, graphene, and other materials listed as suitable additives herein).A particular example of a core-shell nanowire is one with a silver coreand an Au shell (or a platinum shell or another type of shell)surrounding the silver core to reduce or prevent oxidation of the silvercore. Another example of a core-shell nanowire is one with a silver core(or a core formed of another metal or other electrically conductivematerial), with a shell or other coating, formed of one or more of thefollowing: (a) conducting polymers, such aspoly(3,4-ethylenedioxythiophene) (or PEDOT) and polyaniline (or PANI);(b) conducting oxides, chalcogenides, and ceramics (e.g., deposited bysol-gel, chemical vapor deposition, physical vapor deposition,plasma-enhanced chemical vapor deposition, or chemical bath deposition),such as ITO, ZnO:Al, ZnO:In, SnO:F, SnO:Sb, and CdSn; (c) insulators inthe form of ultra-thin layers, such as polymers, SiO₂, BaTiO, and TiO₂;and (d) thin layers of metals, such as Au, Cu, Ni, Cr, Mo, and W. Suchcoated or core-shell form of nanowires can be desirable to impartelectrical conductivity, while avoiding or reducing adverse interactionswith a host material, such as potential yellowing or other discolorationof ethylene vinyl acetate or another polymer in the presence of a metalsuch as Ag.

In cases where it is desirable to impart spectral shiftingfunctionality, additives can include a phosphor or another luminescentmaterial, which can emit light in response to an energy excitation.Current solar devices can suffer technical limitations on the ability toefficiently convert incident sunlight to useful electrical energy. Onesignificant loss mechanism typically derives from a mismatch between anincident solar spectrum and an absorption spectrum of a photoactivelayer. In particular, photons with energy greater than a bandgap energyof the photoactive layer can lead to the production of photo-excitedcharge carriers with excess energy. Such excess energy is typically notconverted into electrical energy but is rather typically lost as heat.In addition, this heat can raise the temperature of a solar device andreduce the efficiency of the solar device. In conjunction with thesethermalization losses, photons with energy less than the bandgap energyof the photoactive layer are typically not absorbed and, thus, typicallydo not contribute to the conversion into electrical energy. As a result,a small range of the incident solar spectrum around the bandgap energycan be efficiently converted into useful electrical energy. Surfaceembedding of spectral shifting additives allows the alteration of anincident solar spectrum to address this spectral mismatch and to improvesolar power conversion efficiencies. A phosphor can be designed to atleast one of wave guide, redirect, scatter, reflect, and plasmon channelradiation.

Luminescence of a phosphor can occur based on relaxation from excitedelectronic states of atoms or molecules and can include, for example,chemiluminescence, electroluminescence, photoluminescence,thermoluminescence, triboluminescence, and combinations thereof. Forexample, in the case of photoluminescence, which can includefluorescence and phosphorescence, luminescence can be based on a lightexcitation, such as absorption of sunlight. Phosphors includedown-shifting materials, namely those that emit light at a lower energy(or higher wavelength) relative to an energy excitation, and up-shiftingmaterials, namely those that emit light at a higher energy (or shorterwavelength) relative to an enemy excitation. Desirable down-shiftingphosphors include those that absorb photons over a certain range ofenergies and emit photons with energies slightly greater than aboutE_(g), where E_(g) denotes a bandgap energy of a photoactive layer.Desirable up-shifting phosphors include those that absorb photons over acertain range of enemies and emit photons with energies slightly greaterthan about E_(g), where E_(g) again denotes a bandgap energy of aphotoactive layer. For certain applications, multiple photon generationcan yield higher solar power conversion efficiencies, and, in general,can involve a conversion of n_(i) photons to n_(j) photons, where n_(i)and n_(j) are integers, and n_(j)>n_(i). For example, a quantum cuttingmaterial can exhibit down-shifting by absorbing one shorter wavelengthphoton and emitting two or more longer wavelength photons, while adown-conversion material can exhibit down-shifting by absorbing oneshorter wavelength photon and emitting one longer wavelength photon. Asanother example, an up-conversion material can exhibit up-shifting by aprocess where two photons are absorbed and one photon is emitted at ahigher energy.

Suitable phosphors include those that exhibit photoluminescence with arelatively high quantum efficiency, which can refer to a ratio of thenumber of output photons to the number of input photons. Quantumefficiency (or quantum yield) of a phosphor can be characterized withrespect to its “internal” quantum efficiency, which can refer to a ratioof the number of photons emitted by the phosphor to the number ofphotons absorbed by the phosphor. Desirable phosphors can exhibitphotoluminescence with a high internal quantum efficiency that is atleast about 10%, such as at least about 20%, at least about 30%, atleast about 40%, at least about 50%, at least about 60%, at least about70%, or at least about 80%, and up to about 90%, up to about 95%, ormore. Quantum efficiency also can refer to a characteristic of aphotoactive material, namely a ratio of the number of charge carriersproduced by the photoactive material to the number of photons incidentupon, or absorbed by, the photoactive material. Desirable phosphorsinclude those that absorb a range of wavelengths where a photoactivematerial has a low quantum efficiency (e.g., less than about 50%) andemit another range of wavelengths where the photoactive material has ahigh quantum efficiency (e.g., at least about 50%, such as at leastabout 80%). In the case of silicon, for example, desirable phosphorsinclude those with a broad band absorption from about 300 nm to about450 nm and with an emission from about 600 nm to about 800 nm.

Phosphors can be included as nanoparticles (e.g., quantum dots andnanocrystals), dissolved molecular species, suspensions of nano-sized ormicron-sized particles (e.g., crystalline particles or amorphousparticles), or combinations thereof. Phosphors can be provided asmetal-organic compounds (e.g., organolanthanide complexes),organometallic compounds (e.g., a phosphorescent organometallic iridiumcomplex such as Ir(bpy)₃, where bpy stands for bipryidine, and Os and Ptcomplexes of similar structure), semiconductor nanocrystals or quantumdots, organic molecules (e.g., organic dyes), and inorganic crystals orother materials (e.g., rare earth doped ceramics).

FIG. 3 illustrates the AM1.5-G solar spectrum at sea level as a functionof wavelength. The area under the curve that is blacked out representsthe spectrum range captured by a 1.12 eV bandgap silicon photoactivelayer until the double bandgap energy, at which point incident light canproduce excessively thermalized carriers in a solar device. Below thechart are arrows representing absorption and emission spectra peaks ofone up-shifting phosphor (Er³⁺-based ceramic) and one down-shiftingphosphor (Eu³⁺-based phosphor).

Embodiments described herein can address engineering challenges thathave impeded the adoption of phosphors in solar devices, such as:

-   -   1) In some instances, phosphors can have less than ideal        stability. Oxidation (e.g., from Eu²⁺ to Eu³⁺) can occur during        a baking process. Phosphors should be stable and compatible with        baking temperatures of typically 400° C.    -   2) In some instances, rare-earth metals and the purification        processes for lanthanides can be expensive. In fluorescent        lamps, for instance, the rare-earth metals can contribute to the        cost of a final fluorescent lamp by about 20-40%.    -   3) In some instances, rare-earth ions can have low absorption        coefficients (e.g., where 4f-4f transitions of lanthanide ions        are forbidden or weak). Phosphor hosts can be desirable to        minimize reflection and maximize absorption and coupling        efficiency of light into excited carriers. Semiconductor hosts        with band gaps greater than 2.7 eV (e.g., ZnSe 2.7 eV, 6H—SiC        3.0 eV, TiO₂ 3.0-3.2 eV) are desirable for high efficiency        energy transfer from the host conduction band to the excited        level of the rare-earth ion. Sensitizers are desirable to absorb        strongly in the region 300-500 nm and transfer efficiently to        the donor.    -   4) In some instances, parasitic absorption from a host material        is a loss mechanism affecting phosphors incorporated in the host        material, the extent of which varies with layer thickness and        host and luminescent species type.    -   5) In some instances, phosphors can present environmental and        safety concerns, can be incompatible with water or moisture        during synthesis, and can degrade under UV radiation.    -   6) In some instances, concentration quenching for high Yb³⁺        concentrations should be minimized. Inducing clustering by        charge compensation and reducing quenching centers reached        through energy migration over the Yb³⁺ sub-lattice may        ameliorate concentration quenching issues.    -   7) In some instances, the emission wavelength (e.g., 980 nm)        Yb³⁺, while above the band gap of crystalline-Si, can suffer        from weak absorption by crystalline-Si at this wavelength,        leading to thicker crystalline-Si layers.    -   8) In some instances, phosphors should be incorporated, into        transparent layers above the solar cell where refractive indices        of the phosphor layer, trapping techniques, and ARCs may be        designed to minimize loss.    -   9) In some instances, light absorbed and re-emitted by the        luminescent species may not be transmitted to the solar cell due        to reflection, where the light lies within the top escape cone        or through the side of the phoshor layer.    -   10) In some instances, organic dyes, while exhibiting relatively        high absorption coefficients, close to unity quantum efficiency,        and easy processability, can have narrow absorption bands, small        Stokes-shift, questionable photostability, and significant        re-absorption losses. In some instances, rare-earth ions can        exhibit low absorption coefficients, and can be expensive and        environmentally hazardous, Quantum dots can be expensive to        produce, can exhibit high re-absorption losses due to the large        overlap between absorption and emission bands, and can exhibit        poor quantum efficiencies.    -   11) in some instances, defects and surface states in inorganic        crystals can serve as electron traps and centers of nonradiative        recombination. Surface excitation, coulombic damage, thermal        quenching, surface oxidation, and other external electronic        reactions can degrade luminescent species.

Table 1 below sets forth additional examples of phosphors ors that canbe included as additives in surface-embedded device components.

TABLE 1 Mechanism Species down-shifting Cr³⁺:Al₂O₃ down-shifting Eu³⁺down-shifting Rhodamine 6G down-shifting Perylene or Naphtalimide dies(e.g., Lumogen-F 241) down-shifting Perylene or Naphtalimide dies (e.g.,Lumogen-F 339) down-shifting Uvitex OB(2,5-thiophenediylbis(5-tert-butyl-1,3- benzoxazole)) down-shiftingHostasol 8G down-shifting Si nanoparticles or other nano-sizedstructures down-shifting Ag:phosphate glass down-shifting Alq3down-shifting TPD (N,N′-diphenyl-N,N′-bis(3-methylphenyl)-[1,1′-biphenyl]-4,4′-diamine) down-shifting Gaq2Cl down-shifting MPIdown-shifting Acrylite SG715, Sumipex 652 down-shifting Bis-MSB,Stilben189, Lumogen-F(570, 650, 083, 170 and 300), Coumarin 307,Fluorescence Yellow CRS040 down-shifting CdSe nanopartieles or othernano-sized structures down-shifting CdS nanoparticles or othernano-sized structures down-shifting ZnSe down-shifting Sm³⁺:KMgF₃down-shifting Tb³⁺ down-shifting Dy³⁺ down-shifting Coumarindown-shifting CRS 040 down-shifting SrAlF₅:Pr³⁺ down-shifting YF₃:Pr³⁺down-shifting NaYF₄:Pr³⁺ down-shifting CaAlF₅:Pr³⁺ down-shiftingNaMgF₃:Pr³⁺ down-shiftintz KMgF₃:Pr³⁺ down-shifting LaZrF₇:Pr³⁺down-shifting Sr:Al₁₂O₁₉:Pr³⁺ down-shifting LiYF₄:Gd³⁺ down-shiftingLiGdF₄:Eu³⁺ down-shifting GdF₃:Eu³⁺ down-shifting BaF₂:Gd³⁺, Eu³⁺down-shifting LiGdF₄:Er³⁺, Tb³⁺ down-shifting ZnS:Ag, Cu, Al, Zndown-shifting YVO₄:Eu down-shifting Y2O₃:Eu down-shifting Cd₃(PO₄)₂:Mndown-shifting BaCl₂:Er³⁺ Up-shifting Er³⁺:Si Up-shifting Tb³⁺:LaF₃Up-shifting Er³⁺:YAlO₃ Up-shifting Er³⁺:Y₂O₃ Up-shifting Er³⁺:LaF₃Up-shifting Er³⁺:LaCl₃ Up-shifting Er³⁺:LaBr₃ Up-shifting Er³⁺:NaYF₄Up-shifting Ti²⁺:MgCl₂ Up-shifting Ti²⁺:NaCl Up-shifting Er³⁺:ZrO₂Up-shifting Rhodamine B Up-shifting Rhodamine 6G Up-shifting PYCUp-shifting APSS

Further examples of phosphors include Er³⁺-based down-shiftingphosphors; lanthanide-containing compounds that are up-shifting ordown-shifting; down-shifting phosphors used in fluorescent lamps (e.g.,Eu³⁺ ions for blue and red emission and Tb³⁺ for green emission, withquantum efficiencies in the range of about 90% to about 93%);CaAl₂O₄:Yb²⁺ and Yb³⁺ co-activated luminescent materials; NaYF₄:Er³⁺(about 20% Er³⁺); Si nanocrystals embedded in a SiO₂ matrix with Er³⁺ion receptors adjacent to the Si nanocrystals; fluorescent dyes;lanthanide ions; lanthanide complexes; nanoantennas; organic antennas;Eu³⁺ phenanthroline (or phen) complexes; [Eu(phen)₂]Cl₃; Tb³⁺ bipyridine(or bpy) complexes; [Tb(bpy)₂]Cl₃; Ca₂BO₃Cl:Ce³⁺; Tb³⁺-based phosphors;Yb³⁺-based phosphors; Er³⁺-Dy³⁺; ORMOSIL:Eu³⁺; Ag; laser dyes; Er; TPD;Y₂O₃:Eu; Eu³⁺; Eu²⁺; Cs₃Y₂Br₉:Eu³⁺—Yb³⁺; Tb—Yb; Pr—Yb; Er—Yb;acrylate-based phosphors; PbSe; PbS; Sm³⁺; SrF₂:Pr³⁺—Yb³⁺; ZnS-basedphosphors, ZnS:Mn, BaMgAl₁₀O₁₇:Eu²⁺ (or BAM) display phosphors;Cu-activated ZnS; Ag-activated ZnS; phosphors with oxide host, nitridehost, oxynitride host, sulfide host, selenide host, halide host,silicate host, and rare-earth metal host; resonant energy transferparticles; or any combination thereof.

Additives can also include, for example, functional agents such asmetamaterials, in place or, in combination with, electrically conductivematerials, semiconductors, and phosphors. Metamaterials and relatedartificial composite structures with particular electromagneticproperties can include, for example, split ring resonators, ringresonators, cloaking devices, nanostructured antireflection layers, highabsorbance layers, perfect lenses, concentrators, microconcentrators,focusers of electromagnetic energy, couplers, and the like. Additivescan also include, for example, materials that reflect, absorb, orscatter electromagnetic radiation, such as any one or more of infraredradiation, ultraviolet radiation, and X-ray radiation. Such materialsinclude, for example, Ag, Au, Ge, TiO₂, Si, Al₂O₃, CaF₂, ZnS, GaAs,ZnSe, KCl, ITO, tin oxide, ZnO, MgO, CaCO₃, benzophenones,benzotriazole, hindered amine light stabilizers, cyanoacrylate,salicyl-type compounds, Ni, Pb, Pd, Bi, Ba, BaSO₄, steel, U, Hg, metaloxides, or any combination thereof. Additional examples of materials foradditives include PhSO₄, SnO₂, Ru, As, Te, In, Pt, Se, Cd, S, Sn, Zn,copper indium diselenide (“CIS”), Cr, Ir, Nd, Y, ceramics (e.g., aglass), silica, or any combination thereof.

Additives can also include, for example, polymer-containing nanotubes,polymer-containing nanoparticles, polymer-containing nanowires,semiconducting nanotubes, insulated nanotubes, nanoantennas, additivesformed of ferromagnetic materials, additives formed of a ferromagneticcore and a highly conducting shell, organometallic nanotubes, metallicnanoparticles or microparticles, additives formed of piezoelectricmaterials, additives formed of quantum dots, additives with dopants,optical concentrating and trapping structures, optical rectums,nano-sized flakes, nano-coaxial structures, waveguiding structures,metallic nanocrystals, semiconducting nanocrystals, as well as additivesformed of multichromic agents, oxides, chemicochromic agents, alloys,piezochromic agents, thermochromic agents, photochromic agents,radiochromic agents, electrochromic agents, metamaterials, silvernitrate, magnetochromic agents, toxin neutralizing agents, aromaticsubstances, catalysts, wetting agents, salts, gases, liquids, colloids,suspensions, emulsions, plasticizers, UV-resistance agents, luminescentagents, antibacterial agents, antistatic agents, behentrimoniumchloride, cocamidopropyl betaine, phosphoric acid esters, phylethyleneglycol ester, polyols, dinonylnaphthylsulfonic acid, rutheniummetalorganic dye, titanium oxide, scratch resistant agents, graphene,copper phthalocyanine, anti-fingerprint agents, anti-fog agents, tintingagents, anti-reflective agents, infrared-resistant agents, highreflectivity agents, optical filtration agents, fragrance, de-odorizingagents, resins, lubricants, solubilizing agents, stabilizing agents,surfactants, fluorescent agents, activated charcoal, toner agents,circuit elements, insulators, conductors, conductive fluids, magneticadditives, electronic additives, plasmonic additives, dielectricadditives, resonant additives, luminescent molecules, fluorescentmolecules, cavities, lenses, cold cathodes, electrodes, nanopyramids,resonators, sensors, actuators, transducers, transistors, lasers,oscillators, photodetectors, photonic crystals, conjugated polymers,nonlinear elements, composites, muitilayers, chemically inert agents,refractive index modifiers, phase-shifting structures, amplifiers,modulators, switches, photovoltaic cells, light-emitting diodes,couplers, antiblock and antislip agents (e.g., diatomaceous earth, talc,calcium carbonate, silica, and silicates); slip agents and lubricants(e.g., fatty acid amides, erucamide, oleamide, fatty acid esters,metallic stearates, waxes, and amide blends), antioxidants (e.g.,amines, phenolics, organophosphates, thioesters, butylatedhydroxytoluene (or BHT), and deactivators), antistatic agents (e.g.,cationic antistats, quaternary ammonium salts and compounds,phosphonium, sulfonium, anionic counterstats, electrically conductivepolymers, amines, and fatty acid esters), biocides (e.g.,10,10′-oxybisphenoxarsine (or OBPA), amine-neutralized phosphate, zinc2-pyridinethianol-1-oxide (or zinc-OMADINE),2-n-octyl-4-isothiazolin-3-one, DCOIT, TRICLOSAN, CAPTAN, and FOLPET),light stabilizers (e.g., ultraviolet absorbers, benzophenone,benzotriazole, benzoates, salicylates, nickel organic complexes,hindered amine light stabilizers (or HALS), and nickel-containingcompounds), electrically conducting polymer (e.g., polyaniline,poly(acetylene), poly(pyrrole), poly(thiophene), poly(p-phenylenesulfide), poly(p-phenylene vinylene) (or PPV), poly(3-alkylthiophene),olyindole, polypyrene, polycarbazole, polyazulene, polyazepine,poly(fluorene), polynaphthalene, melanins,poly(3,4-ethylenedioxythiophene) (or PEDOT), poly(styrenesulfonate) (orPSS), PEDOT-PSS, PEDOT-polymethacrylic acid (or PEDOT-PMA),poly(3-hexylthiophene) (or P3HT), poly(3-octylthiophene) (or P3OT),poly(C-61-butyric acid-methyl ester) (or PCBM), andpoly[2-methoxy-5-(2′-ethyl-hexyloxy)-1,4-phenylene vinylene] (orMEH-PPV)), any material listed as a suitable host material herein, orany combination thereof.

For certain implementations, high aspect ratio additives are desirable,such as in the form of nanowires, nanotubes, and combinations thereof.For example, desirable additives include nanotubes formed of carbon orother materials (e.g., MWNTs, SWNTs, graphitized MWNTs, graphitizedSWNTs, modified MWNTs, modified SWNTs, and polymer-containingnanotubes), nanowires formed of a metal, a metal oxide, a metal alloy,or other materials (e.g., Ag nanowires, Cu nanowires, zinc oxidenanowires (undoped or doped by, for example, aluminum, boron, fluorine,and others), tin oxide nanowires (undoped or doped by, for example,fluorine), cadmium tin oxide nanowires, ITO nanowires,polymer-containing nanowires, and Au nanowires), as well as othermaterials that are electrically conductive or semiconducting and havinga variety of shapes, whether cylindrical, spherical, pyramidal, orotherwise. Additional examples of additives include those formed ofactivated carbon, graphene, carbon black, ketjen black, andnanoparticles formed of a metal, a metal oxide, a metal alloy, or othermaterials (e.g., Ag nanoparticles, Cu nanoparticles, zinc oxidenanoparticles, ITO nanoparticles, and Au nanoparticles).

In general, a host material can have a variety of shapes and sizes, canbe transparent, translucent, or opaque, can be flexible, bendable,foldable or rigid, can be electromagnetically opaque orelectromagnetically transparent, and can be electrically conductive,semiconducting, or insulating. The host material can be in the form of alayer, a film, or a sheet serving as a substrate, or can be in the formof a coating or multiple coatings disposed on top of a substrate oranother material. Examples of suitable host materials include organicmaterials, inorganic materials, and hybrid organic-inorganic materials.For example, a host material can include a thermoplastic polymer, athermoset polymer, an elastomer, or a copolymer or other combinationthereof, such as selected from polyolefin, polyethylene (or PE),polypropylene (or PP), ethylene vinyl acetate (or EVA), an ionomer,polyvinyl butyral (or PVB), polyacrylate, polyester, polysulphone,polyamide, polyimide, polyurethane, polyvinyl, fluoropolymer,polycarbonate (or PC), polysulfone, polylactic acid, polymer based onallyl diglycol carbonate, nitrile-based polymer, acrylonitrile butadienestyrene (or ABS), phenoxy-based polymer, phenylene ether/oxide, aplastisol, an organosol, a plastarch material, a polyacetal, aromaticpolyamide, polyamide-imide, polyarylether, polyetherimide,polyarylsulfone, polybutylene, polyketone, polymethylpentene,polyphenylene, polystyrene, high impact polystyrene, polymer based onstyrene maleic anhydride, polymer based on polyallyl diglycol carbonatemonomer, bismaleimide-based polymer, polyallyl phthalate, thermoplasticpolyurethane, high density polyethylene, low density polyethylene,copolyesters (e.g., available under the trademark Tritan™), polyvinylchloride (or PVC), acrylic-based polymer, polyethylene terephthalateglycol (or PETG), polyethylene terephthalate (or PET), epoxy,epoxy-Containing resin, melamine-based polymer, silicone and othersilicon-containing polymers polysilanes and polysilsesquioxanes),polymers based on acetates, polypropylene fumarate), poly(vinylidenefluoride-trifluoroethylene), poly-3-hydroxybutyrate polyesters,polyamide, polycaprolactone, polyglycolic acid (or PGA), polyglycolide,polylactic acid (or PLA), polylactide acid plastics, polyphenylenevinylene, electrically conducting polymer (e.g., polyaniline,poly(acetylene), poly(pyrrole), poly(thiophene), poly(p-phenylenesulfide), poly(p-phenylene vinylene) (or PPV), poly(3-alkylthiophene),olvindole, polypyrene, polyearbazole, polyazulene, polyazepine,poly(fluorene), polynaphthalene, melanins,poly(3,4-ethylenedioxythiophene) (or PEDOT), poly(styrenesulfonate) (orPSS), PEDOT-PSS, PEDOT-polymethacrylic acid (or PEDOT-PMA),poly(3-hexylthiophene) (or P3HT), poly(3-octylthiophene) (or P3OT),poly(C-61-butyric acid-methyl ester) (or PCBM), andpoly[2-methoxy-5-(2′-ethyl-hexyloxy)-1,4-phenylene vinylene] (orMEH-PPV)), polyolefins, liquid, crystal polymers, polyurethane,polyester, copolyester, poly(methyl mechacrylate) copolymer,tetrafluoroethylene-based polymer, sulfonated tetrafluoroethylenecopolymer, ionomers, fluorinated ionomers, polymer corresponding to, orincluded in, polymer electrolyte membranes, ethanesulfonylfluoride-based polymer, polymer based on2-[1-[difluoro-[(trifluoroethenyl)oxy]methyl]-1,2,2,2-tetrafluoroethoxy]-1,1,2,2,-tetrafluoro-(with tetrafluoro ethylene,tetrafluoroethylene-perfluoro-3,6-dioxa-4-methyl-7-octenesulfonic acidcopolymer), polypropylene, polybutene, polyisobutene, polyisoprene,polystyrene, polylactic acid, polyglycolide, polyglycolic acid,polycaprolactone, polymer based on vinylidene fluoride, polymer based ontrifluoroethylene, poly(vinylidene fluoride-trifluoroethylene),polyphenylene vinylene, polymer based on copper phthalocyanine,graphene, poly(propylene fumarate), cellophane, cuprammonium-basedpolymer, rayon, and biopolymers (e.g., cellulose acetate (or CA),cellulose acetate butyrate (or CAB), cellulose acetate propionate (orCAP), cellulose propionate (or CP), polymers based on urea, wood,collagen, keratin, elastin, nitrocellulose, plastarch, bamboo,bio-derived polyethylene, carbodiimide, cartilage, cellulose nitrate,cellulose, chitin, chitosan, connective tissue, copper phthalocyanine,cotton cellulose, elastin, glycosaminoglycans, linen, hyaluronic acid,nitrocellulose, paper, parchment, plastarch, starch, starch-basedplastics, vinylidene fluoride, and viscose), or any monomer, copolymer,blend, or other combination thereof. Additional examples of suitablehost materials include ceramic (e.g., SiO₂-based glass; SiO_(x)-basedglass; TiO_(x)-based glass; other titanium, cerium, magnesium analoguesof SiO_(x)-based glass; spin-on glass; glass formed from sol-gelprocessing, silane precursor, siloxane precursor, silicate precursor,tetraethyl orthosilicate, silane, siloxane, phosphosilicates, spin-onglass, silicates, sodium silicate, potassium silicate, a glassprecursor, a ceramic precursor, silsesquioxane, metallasilsesquioxanes,polyhedral oligomeric silsesquioxanes, halosilane, polyimide, PMMAphotoresist, sol-gel, silicon-oxygen hydrides, silicones, stannoxanes,silathianes, silazanes, polysilazanes, metallocene, titanocenedichloride, vanadocene dichloride; and other types of glasses), ceramicprecursor, polymer-ceramic composite, polymer-wood composite,polymer-carbon composite (e.g., formed of ketjen black, activatedcarbon, carbon black, graphene, and other forms of carbon),polymer-metal composite, polymer-oxide, or any combination thereof.

A host material can be, for example, n-doped, p-doped, or un-doped.Embedded additives can be, for example, n-doped, p-doped, or un-doped.If the host material is electrically conductive or semiconducting,additives that are n-doped, p-doped, or both, can be used to form p-njunctions for solar devices and other types of electronic andoptoelectronic devices.

At least one difference between the configuration of FIG. 1A and certainsurface-embedded device components described herein (e.g., asillustrated in FIG. 1D through FIG. 1I and FIG. 2A through FIG. 2H) isthat, characteristic of bulk incorporation, the device layer 104 of FIG.1A has the additives 102 distributed randomly and relatively uniformlythroughout the device layer 104. In contrast, in the surface-embeddeddevice components described herein, additives can be largely confined toa “planar” or “planar-like” embedding region of a host material, leadingto decreased topological disorder of the additives and increasedoccurrence of junction formation between the additives for improvedelectrical conductivity. Although an embedding region is sometimesreferred as “planar,” it will be understood that such embedding regionis typically not strictly two-dimensional, as the additives themselvesare typically three-dimensional. Rather, “planar” can be used in arelative sense, with a relatively thin, slab-like (or layered) localconcentration of the additives within a certain region of the hostmaterial, and with the additives largely absent from a remainder of thehost material. It will also be understood that an embedding region canbe referred as “planar,” even though such an embedding region can have athickness that is greater than (e.g. several times greater than) acharacteristic dimension of additives, such as in FIG. 1F, FIG. 2A, andFIG. 2B. An embedding region can be located adjacent to one side of ahost material, adjacent to a middle of the host material, or adjacent toany arbitrary location along a thickness direction of the host material,and multiple embedding regions can be located adjacent to one another orspaced apart from one another within the host material. Each embeddingregion can include one or more types of additives, and embedding regions(which are located in the same host material) can include differenttypes of additives. By confining electrically conductive additives to aset of “planar” embedding regions of a host material (as opposed torandomly throughout the host material), a higher electrical conductivitycan be achieved for a given amount of the additives per unit of area.Any additives not confined to an embedding region represent an excessamount of additives that can be omitted.

By confining spectral shifting additives to a set of “planar” embeddingregions of a host material (as opposed to randomly throughout the hostmaterial), higher solar power conversion efficiencies can be achievedfor a given amount of the additives per unit of area of a solar device,by reducing instances of self-absorption or quenching. For example, andbecause a luminescent species can be largely confined to an embeddingregion adjacent to a top surface of the host material, little or nofurther species are present below the top embedded species to re-absorban emission spectra of the top embedded species. The drasticallydecreased re-absorption due to the confinement of luminescent speciesinto a “planar” embedding region can effectively addresses the issue ofhigh concentration quenching. Also, a down-shifting species embeddedadjacent to a top surface of a device layer, such as an encapsulantlayer of a solar device, can increase a UV-resistance of a polymer ofthe device layer, by converting UV radiation of incident sunlight tovisible light. Conventional UV-stabilizers or absorbers can beeliminated, decreased in concentration, or included at the sameconcentration.

At least one difference between the configuration of FIG. 1B and certainsurface-embedded structures described herein (e.g., as illustrated inFIG. 1D through FIG. 1I and FIG. 2A through FIG. 2H) is that,characteristic of a conventional coating, the device layer 110 of FIG.1B has the additives 108 mixed throughout the device layer 110, which isdisposed on top of the device layer 112. Referring to the device layer110 itself, the layer 110 features a configuration similar to that shownin FIG. 1A for the case of bulk incorporation, with the additives 108distributed, randomly and relatively uniformly throughout the layer 110.In contrast, in certain surface-embedded device components describedherein, additives are not located uniformly throughout a coating, butrather can be largely confined to a “planar” or “planar-like” embeddingregion of a device layer, without any coating or other secondarymaterial needed for binding the additives to the device layer, while, inother surface-embedded structures (e.g., as illustrated in FIG. 1G andFIG. 2G), additives can be largely confined to a “planar” or“planar-like” embedding region of a coating, rather than locateduniformly throughout the coating. Confining electrically conductiveadditives to a “planar” or “planar-like” embedding region leads todecreased topological disorder of the additives and increased occurrenceof junction formation between the additives for improved electricalconductivity. Also, confining spectral shifting additives to a “planar”or “planar-like” embedding region allows reduced self-absorption andincreased UV-resistance.

Moreover, the device layer 110 of FIG. 1B can be susceptible to damage,as an exposed material on top of the layer 110 can be readily removedwith scotch tape, a sticky or abrasive force, or other force, and canhave a tendency to migrate off the surface. The device layer 110containing the additives 108 can also delaminate, crack, peel, bubble,or undergo other deformation, which can be overcome by certainsurface-embedded device components described herein in which additivesare directly embedded into a device layer, without any coating or othersecondary material needed for the purposes of binding. For example, apotential issue encountered during the fabrication of electronic deviceson polyimide layers is the adhesion of adjacent layers. Peeling anddelamination can occur for thin films or other layers deposited onpolyimide layers. Surface-embedded device components described hereinprovide improved mechanical durability and robustness of devicesfabricated on polyimide layers. The advantages of surface embedding areapplicable to polyimide substrates, as well as other polymer or polymercomposite substrates. By directly and durably embedding active orfunctional additives into a polyimide layer (rather than depositing as afilm on top of the polyimide layer), embodiments overcome the poor ofadhesion of thin films to polyimide and obviate the use of tie-coats,primers, or other secondary or immediate layers to promote adhesion thatcan be detrimental to device performance and increase costs. Referringto FIG. 1B, the topological disorder of the additives 108 in which someof the additives 108 extend out from the surface of the layer 110 canresult in roughness, cause electrical shorts, and prevent intimatecontact with an adjacent device layer. This is in contrast to thesurface-embedded device components described herein, which can featuredurable, smooth surfaces. In the case where additives are substantiallyor fully embedded into a host material (e.g., as illustrated in FIG. 1Eand FIG. 1F), an embedding surface of the resulting surface-embeddedstructure is quite smooth (e.g., having a smoothness or a roughnesssubstantially comparable to that of the host material in the absence ofthe embedded additives), with none, no greater than about 1%, no greaterthan about 5%, no greater than about 10%, no greater than about 25%, orno greater than about 50% of a surface area of the embedding surfaceoccupied by exposed additives (e.g., as measured by taking a top view ofthe embedding surface or other 2-dimensional representation of theembedding surface, and determining percentage surface area coveragearising from the exposed additives).

At least one difference between the configuration of FIG. 1C and certainsurface-embedded device components described herein (e.g., asillustrated in FIG. 1D through FIG. 1I and FIG. 2A through FIG. 2H) isthat, characteristic of surface deposition, the additives 116 aredisposed on top of the device layer 118, without any embedding of theadditives 116 into the layer 118. The surface-deposited structure 114 ofFIG. 1C can be susceptible to damage, as the deposited material on topof the layer 118 can be readily removed with scotch tape, a sticky orabrasive force, or other force, and can have a tendency to migrate offthe surface. Also, the surface of the surface-deposited structure 114 isquite porous (e.g., arising from gaps between the surface-depositedadditives 116, from stacking of the additives 116 on top of one another,or both), which can create challenges in achieving adequate infiltrationof another material coated or otherwise applied on top of thesurface-deposited additives 116, thereby resulting in voids or otherinterfacial defects. Moreover, the surface of the surface-depositedstructure 114 can be quite rough, which can cause electrical shorts andprevent intimate contact with an adjacent device layer. This is incontrast to the surface-embedded device components described herein,which can feature durable, relatively non-porous, smooth surfaces. Inthe case where additives are substantially or fully embedded into a hostmaterial (e.g., as illustrated in FIG. 1F and FIG. 1F), an embeddingsurface of the resulting surface-embedded structure is quite smooth(e.g., having a smoothness or a roughness substantially comparable tothat of the host material in the absence of the embedded additives),with none, no greater than about 1%, no greater than about 5%, nogreater than about 10%, no greater than about 25%, or no greater thanabout 50% of a surface area of the embedding surface occupied by exposedadditives (e.g., as measured by taking a top view of the embeddingsurface or other 2-dimensional representation of the embedding surface,and determining percentage surface area coverage arising from theexposed additives). Moreover, the surface-deposited structure 114 canhave a higher sheet resistance or lower conductivity than thesurface-embedded device components described herein.

In some embodiments, surface-embedded device components can haveadditives embedded into a host material from about 10% (or less, such asfrom about 0.1%) by volume into an embedding surface and up to about100% by volume into the embedding surface, and can have the additivesexposed at varying surface area coverage, such as from about 0.1% (orless) surface area coverage up to about 99.9% (or more) surface areacoverage. For example, in terms of a volume of an additive embeddedbelow the embedding surface relative to a total volume of the additive,at least one additive can have an embedded volume percentage (or apopulation of the additives can have an average embedded volumepercentage) in the range of about 10% to about 100%, such as from 10% toabout 50%, or from about 50% to about 100%.

In some embodiments, surface-embedded device components can have anembedding region with a thickness greater than a characteristicdimension of additives used (e.g., for nanowires, greater than adiameter of an individual nanowire or an average diameter across thenanowires), with the additives largely confined, to the embedding regionwith the thickness less than an overall thickness of the host material.For example, the thickness of the embedding region can be no greaterthan about 80% of the overall thickness of the host material, such as nogreater than about 50%, no greater than about 40%, no greater than about30%, no greater than about 20%, no greater than about 10%, or no greaterthan about 5% of the overall thickness.

In some embodiments, additives can be embedded into a host material byvarying degrees relative to a characteristic dimension of the additivesused (e.g., for nanowires, relative to a diameter of an individualnanowire or an average diameter across the nanowires). For example, interms of a distance of a furthest embedded point on an additive below anembedding surface, at least one additive can be embedded to an extent ofmore than about 100% of the characteristic dimension, or can be embeddedto an extent of not more than about 100% of the characteristicdimension, such as at least about 5% or about 10% and up to about 80%,up to about 50%, or up to about 25% of the characteristic dimension. Asanother example, a population of the additives, on average, can beembedded to an extent of more than about 100% of the characteristicdimension, or can be embedded to an extent of not more than about 100%of the characteristic dimension, such as at least about 5% or about 10%and up to about 80%, up to about 50%, or up to about 25% of thecharacteristic dimension. As will be understood, the extent at whichadditives are embedded into a host material can impact a roughness of anembedding surface, such as when measured as an extent of variation ofheights across the embedding, surface (e.g., a standard deviationrelative to an average height). Comparing, for example, FIG. 1D versusFIG. 1C, a roughness of the surface-embedded structure 120 of FIG. 1D isless than a characteristic dimension of the partially embedded additives130, while a roughness of the structure 114 of FIG. 1C is at least acharacteristic dimension of the superficially deposited additives 116and can be about 2 times (or more) the characteristic dimension (e.g.,as a resulting of stacking of the additives 116 on top of one another).

In some embodiments, at least one additive can extend out from anembedding surface of a host material from about 0.1 nm to about 1 cm,such as from about 1 nm to about 50 nm, from about 50 nm to 100 nm, orfrom about 100 nm to about 100 microns. In other embodiments, apopulation of additives, on average, can extend out from an embeddingsurface of a host material from about 0.1 nm to about 1 cm, such as fromabout 1 nm to about 50 nm, from about 50 nm to 100 nm, or from about 100nm to about 100 microns. In other embodiments, substantially all of asurface area of a host material (e.g., an area of an embedding surface)is occupied by additives. In other embodiments, up to about 100% or upto about 75% of the surface area is occupied by additives, such as up toabout 50% of the surface area, up to about 25% of the surface area, upto about 10%, up to about 5%, up to about than 3% of the surface area,or up to about 1% of the surface area is occupied by additives.Additives need not extend out from an embedding surface of a hostmaterial, and can be localized entirely below the embedding surface Thedegree of embedding and surface coverage of additives for asurface-embedded structure can be selected in accordance with aparticular device component or application. For example, a devicecomponent operating based on spectral shifting of surface-embeddedadditives can specify a deeper degree of embedding and lower surfacecoverage of the additives, while a device component operating based onthe flow of an electric current through or across a surface can specifya lesser degree of embedding and higher surface coverage of theadditives.

In some embodiments, if nanowires are used as additives, characteristicsthat can influence electrical conductivity and other desirablecharacteristics include, for example, nanowire density or loading level,surface area coverage, nanowire length, nanowire diameter, uniformity ofthe nanowires, material type, and purity. There can be a preference fornanowires with a low junction resistance and a low bulk resistance insome embodiments. For attaining higher electrical conductivity whilemaintaining high transparency, thinner diameter, longer length nanowirescan be used (e.g., with relatively large aspect ratios to facilitatenanowire junction formation and in the range of about 50 to about 2,000,such as from about 50 to about 1,000, or from about 100 to about 800),and metallic nanowires, such as Ag, Cu, and Au nanowires, can be used,Characteristics of nanowires also can be selected or adjusted to providelight scattering, such as when incorporated within a device layerserving as a backreflector of a solar device. Using nanowires asadditives to form nanowire networks, such as Ag nanowire networks, canbe desirable for some embodiments. Other metallic nanowires,non-metallic nanowires, such as ZnO, ZnO(i), ZnO:Al, ZnO:B, SnO₂:F,Cd₂SnO₄, CdS, ZnS, TiO₂, ITO, and other oxide nanowires, also can beused. Additives composed of semiconductors with bandgaps outside thevisible optical spectrum energies (e.g., <1.8 eV and >3.1 eV) orapproximately near this range, can be used to create device layers withhigh optical transparency in that visible light will typically not beabsorbed by the bandgap energies or by interfacial traps therein.Various dopants can be used to tune the conductivity of theseaforementioned semiconductors, taking into account the shifted Fermilevels and bandgap edges via the Moss-Burstein effect. The nanowires canbe largely uniform or monodisperse in terms of dimensions (e.g.,diameter and length), such as the same within about 5% (e.g., a standarddeviation relative to an average diameter or length), the same withinabout 10%, the same within about 15%, or the same within about 20%.Purity can be, for example, at least about 50%, at least about 75%, atleast about 85%, at least about 90%, at least about 95%, at least about99%, at least about 99.9%, or at least about 99.99%. Surface areacoverage of nanowires can be, for example, up to about 100%, less thanabout 100%, up to about 75%, up to about 50%, up to about 25%, up toabout 10%, up to about 5%, up to about 3%, or up to about 1%. Agnanowires can be particularly desirable for certain embodiments, sincesilver oxide, which can form (or can be formed) on surfaces of Agnanowires as a result of oxidation, is electrically conductive. Also,core-shell nanowires (e.g., silver core with Au or platinum shell) alsocan decrease junction resistance.

In some embodiments, if nanotubes are used as additives (whether formedof carbon, a metal, a metal alloy, a metal oxide, or another material),characteristics that can influence electrical conductivity and otherdesirable characteristics include, for example, nanotube density orloading level, surface area coverage, nanotube length, nanotube innerdiameter, nanotube outer diameter, whether single-walled or multi-wallednanotubes are used, uniformity of the nanotubes, material type, andpurity. There can be a preference for nanotubes with a low junctionresistance in sonic embodiments. For reduced scattering in the contextof certain devices such as displays, nanotubes, such as carbonnanotubes, can be used to form nanotube networks. Alternatively, or incombination, smaller diameter nanowires can be used to achieve a similarreduction in scattering relative to the use of nanotubes.Characteristics of nanotubes also can be selected or adjusted to providelight scattering, such as when incorporated within a device layerserving as a backreflector of a solar device. Nanotubes can be largelyuniform or monodisperse in terms of dimensions (e.g., outer diameter,inner diameter, and length), such as the same within about 5% (e.g., astandard deviation relative to an average outer/inner diameter orlength), the same within about 10%, the same within about 15%, or thesame within about 20%. Purity can be, for example, at least about 50%,at least about 75%, at least about 85%, at least about 90%, at leastabout 95%, at least about 99%, at least about 99.9%, or at least about99.99%. Surface area coverage of nanotubes can be, for example, up toabout 100%, less than about 100%, up to about 75%, up to about 50%, upto about 25%, up to about 10%, up to about 5%, up to about 3%, or up toabout 1%.

it should be understood that the number of additive types can be variedfor a given device component or application. For example, any, or acombination, of Ag nanowires, Cu nanowires, and Au nanowires can be usedalong with ITO nanoparticles to yield high optical transparency and highelectrical conductivity. Similar combinations include, for example, any,or a combination, of Ag nanowires, Cu nanowires, and Au nanowires alongwith any one or more of ITO nanowires, ZnO nanowires, ZnO nanoparticles,Ag nanoparticles, Au nanoparticles, SWNTs, MWNTs, fullerene-basedmaterials (e.g., carbon nanotubes and buckyballs), ITO nanoparticles,and phosphors. The use of ITO nanoparticles or nanowires can provideadditional functionality, such as by serving as a buffer layer to adjusta work function in the context of solar devices or to provide aconductive path for the flow of an electric current, in place of, or incombination with, a conductive path provided by other additives.Virtually any number of different types of additives can be embedded ina host material.

In some embodiments, additives are initially provided as discreteobjects. Upon embedding into a host material, the host material canenvelop or surround the additives such that the additives become alignedor otherwise arranged within a “planar” or “planar-like” embeddingregion. In some embodiments for the case of additives such as nanowires,nanotubes, microwires, microtubes, or other additives with an aspectratio greater than 1, the additives become aligned such that theirlengthwise or longitudinal axes are largely confined to within a rangeof angles relative to a horizontal plane, or another planecorresponding, or parallel, to a plane of an embedding surface. Forexample, the additives can be aligned such that their lengthwise orlongest-dimension axes, on average, are confined to a range from about−45° to about +45° relative to the horizontal plane, such as from about−35° to about +35°, from about −25° to about +25°, from about −15° toabout +15°, from about −5° to about +5°, or from about −1° to about +1°.In this example, little or substantially none of the additives can havetheir lengthwise or longitudinal axes oriented outside of the range fromabout −45° to about +45° relative to the horizontal plane. Within theembedding region, neighboring additives can contact one another in someembodiments. Such contact can be improved using longer aspect ratioadditives, while maintaining a relatively low surface area coverage fordesired transparency. In some embodiments, contact between additives,such as nanowires, nanoparticles, microwires, and microparticles, can beincreased through sintering or annealing, such as low temperaturesintering at temperatures of about 50° C., about 125° C., about 150° C.,about 175° C., or about 200° C., or in the range of about 50° C. toabout 125° C., about 100° C. to about 125° C., about 125° C. to about150° C., about 150° C. to about 175° C., or about 175° C. to about 200°C., flash sintering, sintering through the use of redox reactions tocause deposits onto additives to grow and fuse the additives together,or any combination thereof. For example, in the case of Ag or Auadditives, Ag ions or Au ions can be deposited onto the additives tocause the additives to fuse with neighboring additives. High temperaturesintering at temperatures at or above about 200° C. is alsocontemplated. It is also contemplated that little or no contact isneeded for certain applications and devices, where charge tunneling orhopping provides sufficient electrical conductivity in the absence ofactual contact, or where a host material or a coating on top of the hostmaterial may itself be electrically conductive. Such applications anddevices can operate with a sheet resistance up to about 10⁶ Ω/sq ormore. Individual additives can be separated by electrical and quantumbarriers for electron transfer.

The following provides additional advantages of the surface-embeddeddevice components described herein, relative to the configurationsillustrated in FIG. 1A through FIG. 1C. Unlike the configuration of FIG.1A, a uniform distribution of additives throughout an entire bulk of ahost material is not required to attain desired characteristics. Indeed,there is a preference in at least some embodiments that additives arelargely confined to a “planar” or “planar-like” embedding region of ahost material. In practice, it can be difficult to actually attain anuniform distribution as depicted in FIG. 1A, arising from non-uniformmixing and agglomeration and aggregation of additives. Unlike theconfiguration of FIG. 1B, additives can be embedded into a hostmaterial, rather than mixed throughout a coating and applied on top ofthe host material. In embedding the additives in such manner, theresulting surface-embedded device component can have a higherdurability, better adhesion, and superior mechanical integrity. Also,similar to issues associated with bulk incorporation, conventionalcoatings can be susceptible to non-uniform mixing and agglomeration,which can be avoided or reduced with the surface-embedded devicecomponents described herein. By providing a high uniformity of additivedistribution within an embedding region, the disclosed embodiments allowimproved reliability across devices, as well as thinner composite layersdue to surface embedding compared to discrete coatings or bulkincorporation. This high uniformity within an embedding region isattained at least in part due to the surface embedding methods disclosedin the following, which can embed additives into an embedding surfaceand reduce or prevent subsequent additive migration or agglomeration.Furthermore, the topological disorder of additives in the z-direction ofconventional coatings can result in roughness, particularly on thenanometer and micron level. In contrast, and arising, for example, fromembedding of additives and alignment of the additives within a hostmaterial, the surface-embedded device components can have a decreasedroughness compared to conventional coatings, thereby serving to avoid orreduce instances of device failure (e.g., shunting from nanowirepenetration of a device). Unlike the configuration of FIG. 1C, additivesare partially or fully embedded into a host material, rather thansuperficially disposed on top of a surface, resulting in a decreasedroughness compared to superficially deposited additives and higherdurability and conductivity. In some embodiments, when embeddingnanowires, polymer chains of a host material can hold the nanowirestogether, pulling them closer and increasing conductivity. Heating adevice layer also can result in the polymer chains moving the nanowireseven closer together.

The surface-embedded device components can be quite durable. In someembodiments, such durability is in combination with rigidity androbustness, and, in other embodiments, such durability is in combinationwith the ability to be flexed, rolled, bent, and folded, amongst otherphysical actions, with, for example, no greater than about 50%, nogreater than about 20%, no greater than about 15%, no greater than about10%, no greater than about 5%, no greater than about 3%, orsubstantially no decrease in transmittance, no greater than about 50%,no greater than about 20%, no greater than about 15%, no greater thanabout 10%, no greater than about 5%, no greater than about 3%, orsubstantially no increase in resistance, and no greater than about 50%,no greater than about 20%, no greater than about 15%, no greater thanabout 10%, no greater than about 5%, no greater than about 3%, orsubstantially no decrease in quantum efficiency. In some embodiments,the surface-embedded device components are largely immune to durabilityissues of conventional coatings, and can survive a standard Scotch TapeTest used in the coatings industry and yield substantially no decrease,or no greater than about 5% decrease, no greater than about 10%decrease, no greater than about 15% decrease, or no greater than about50% decrease in observed transmittance, yield substantially no increase,or no greater than about 5% increase, no greater than about 10%increase, no greater than about 15% increase, or no greater than about50% increase in observed resistance, and yield substantially nodecrease, or no greater than about 5% decrease, no greater than about10% decrease, no greater than about 15% decrease, or no greater thanabout 50% decrease in observed quantum efficiency. In some embodiments,the surface-embedded device components can also survive rubbing,scratching, flexing, physical abrasion, thermal cycling, chemicalexposure, and humidity cycling with substantially no decrease, nogreater than about 50% decrease, no greater than about 20% decrease, nogreater than about 15% decrease, no greater than about 10% decrease, nogreater than about 5% decrease, or no greater than about 3% decrease inobserved transmittance or quantum efficiency, and with substantially noincrease, no greater than about 50% increase, no greater than about 20%increase, no greater than about 15% increase, no greater than about 10%increase, no greater than about 5% increase, or no greater than about 3%increase in observed resistance. This enhanced durability can resultfrom embedding of additives within a host material, such that theadditives are physically or chemically held inside the host material bymolecular chains or other components of the host material. In somecases, flexing or pressing can be observed to increase conductivity.

Another advantage of some embodiments of the surface-embedded devicecomponents is that an electrical percolation threshold can be attainedusing a lesser amount of additives. Stated in another way, electricalconductivity can be attained using less additive material, therebysaving additive material and associated cost and increasingtransparency. As will be understood, an electrical percolation thresholdis typically reached when a sufficient amount of additives is present toallow percolation of electrical charge from one additive to anotheradditive, thereby providing a conductive path across at least portion ofa network of additives. In some embodiments, an electrical percolationthreshold can be observed via a change in slope of a logarithmic plot ofresistance versus loading level of additives as illustrated in theschematic of FIG. 4. A lesser amount of additive material can be usedsince additives are largely confined to a “planar” or “planar-like”embedding region, thereby greatly reducing topological disorder andresulting in a higher probability of inter-additive (e.g. inter-nanowireor inter-nanotube) junction formation compared to the configurations ofFIG. 1A through FIG. 1C. In other words, because the additives areconfined to a thin embedding region in the host material, as opposed todispersed throughout the thickness of the host material, the probabilitythat the additives will interconnect and form junctions can be greatlyincreased. In some embodiments, an electrical percolation threshold canbe attained at a loading level of additives in the range of about 0.001μg/cm² to about 100 μg/cm² or higher), such as from about 0.01 μg/cm² toabout 100 μg/cm², from about 10 μg/cm² to about 100 μg/cm², from 0.01μg/cm² to about 0.4 μg/cm², from about 0.5 μg/cm² to about 5 μg/cm², orfrom about 0.8 μg/cm² to about 3 μg/cm² for certain additives such assilver nano-wires. These loading levels can be varied, according todimensions, material type, spatial dispersion, and other characteristicsof additives.

In addition, a lesser amount of additives can be used (e.g., asevidenced by a thickness of an embedding region) to achieve anetwork-to-bulk transition, which is a parameter representing atransition of a thin layer from exhibiting effective material propertiesof a sparse two-dimensional conducting network to one exhibitingeffective properties of a three-dimensional conducting bulk material. Byconfining additives (e.g., Ag nanowires, Cu nanowires, multi-walledcarbon nanotubes (“MWCNTs”), singled-walled carbon nanotubes (“SWCNTs”),or any combination thereof) to a “planar” or “planar-like” embeddingregion, a lower sheet resistance can be attained at specific levels ofsolar flux-weighted transmittance. Furthermore, in some embodiments,carrier recombination can be reduced with the surface-embedded devicecomponents due to the reduction or elimination of interfacial defectsassociated with a separate coating or other secondary material intowhich additives are mixed.

To expound farther on these advantages, a network of additives can becharacterized by a topological disorder and by contact resistance.Topologically, above a critical density of additives and above acritical density of additive-additive (e.g., nanowire-nanowire,nanotube-nanotube, or nanotube-nanowire) junctions, electrical currentcan readily flow from a source to a drain. A “planar” or “planar-like”network of additives can reach a network-to-bulk transition with areduced thickness, represented in terms of a characteristic dimension ofthe additives (e.g., for nanowires, relative to a diameter of anindividual nanowire or an average diameter across the nanowires). Forexample, an embedding region can have a thickness up to about 5 times(or more) the characteristic dimension, such as up to about 4 times, upto about 3 times, or up to about 2 times the characteristic dimension,and down to about 0.05 or about 0.1 times the characteristic dimension,allowing devices to be thinner while increasing optical transparency andelectrical conductivity. Accordingly, the surface-embedded devicecomponents described herein provide, in sonic embodiments, an embeddingregion with a thickness up to about n×d (in terms of nm) within whichare localized additives having a characteristic dimension of d (in termsof nm), where n=2, 3, 4, 5, or higher.

Another advantage of some embodiments of the surface-embedded devicecomponents is that, for a given level of electrical conductivity, thecomponents can yield higher transparency. This is because less additivematerial can be used to attain that level of electrical conductivity, inview of the efficient formation of additive-additive junctions for agiven loading level of additives. As will be understood, a transmittanceof a thin conducting material (e.g., in the form of a film) can beexpressed as a function of its sheet resistance R and an opticalwavelength, as given by the following approximate relation for a thinfilm:

$\begin{matrix}{{T(\lambda)} = \left( {1 + {\frac{188.5}{R_{D}}\frac{\sigma_{Op}(\lambda)}{\sigma_{D\; C}}}} \right)^{- 2}} & (1)\end{matrix}$

where σ_(Op) and σ_(DC) are the optical and DC conductivities of thematerial, respectively. In some embodiments, Ag nanowire networkssurface-embedded into flexible transparent substrates can have sheetresistances as low as about 3.2 Ω/sq or about 0.2 Ω/sq, or even lower.In other embodiments, transparent surface-embedded device componentssuitable for solar devices can reach up to about 85% (or more) for solarflux-weighted transmittance T_(solar) and a sheet resistances as low asabout 20 Ω/sq (or below). In still other embodiments, a sheet resistanceof ≦10 Ω/sq at ≧85% (e.g., at least about 85%, at least about 90%, or atleast about 95%, and up to about 97%, about 98%, or more) solarflux-weighted transmittance can be obtained with the surface-embeddedstructures. It will be understood that transmittance can be measuredrelative to other ranges of optical wavelength, such as transmittance ata given wavelength of 550 nm, a human vision or photometric-weightedtransmittance (e.g., from about 350 nm to about 700 nm), solar-fluxweighted transmittance, transmittance at a given wavelength or range ofwavelengths in the infrared range, and transmittance at a givenwavelength or range of wavelengths in the ultraviolet range. It willalso be understood that transmittance can be measured relative to asubstrate (if present) (e.g., accounting for an underlying substratethat is below a host material with surface-embedded additives), or canbe measured relative to air (e.g., without accounting for the underlyingsubstrate). Unless otherwise specified herein, transmittance values aredesignated relative to a substrate (if present), although similartransmittance values (albeit with somewhat higher values) are alsocontemplated when measured relative to air. For some embodiments, aDC-to-optical conductivity ratio of surface-embedded structures can beat least about 100, at least about 115, at least about 300, at leastabout 400, or at least about 500, and up to about 600, up to about 800,or more.

Certain surface-embedded device components can include additives of Agnanowires of average diameter in the range of about 1 nm to about 100nm, about 10 nm to about 80 nm, about 20 nm to about 80 nm, or about 40nm to about 60 nm, and an average length in the range of about 50 nm toabout 1,000 μm, about 50 nm to about 500 μm, about 100 nm to about 100μm, about 500 nm to 50 μm, about 5 μm to about 50 μm, about 20 μm toabout 150 μm, about 5 μm to about 35 μm, about 25 μm to about 80 μm,about 25 μm to about 50 μm, or about 25 μm to about 40 μm. A top of anembedding region can be located about 0.0001 nm to about 100 μm below atop, embedding surface of a host material, such as about 0.01 nm toabout 100 μm below the embedding surface, about 0.1 nm to 100 μm belowthe embedding surface, about 0.1 nm to about 5 μm below the embeddingsurface, about 0.1 nm to about 3 μm below the embedding surface, about0.1 nm to about 1 μm below the embedding surface, or about 0.1 nm toabout 500 nm below the embedding surface. Nanowires embedded into a hostmaterial can protrude from an embedding surface from about 0% by volumeand up to about 90%, up to about 95%, or up to about 99% by volume. Forexample, in terms of a volume of a nanowire exposed above the embeddingsurface relative to a total volume of the nanowire, at least onenanowire can have an exposed volume percentage (or a population of thenanowires can have an average exposed volume percentage) of up to about1%, up to about 5%, up to about 20%, up to about 50%, or up to about 75%or about 95%. At a transmittance of about 85% or greater (e.g., solarflux-weighted transmittance or one measured at another range of opticalwavelengths), a sheet resistance can be no greater than about 500 Ω/sq,no greater than about 400 Ω/sq, no greater than about 350 Ω/sq, nogreater than about 300 Ω/sq, no greater than about 200 Ω/sq, no greaterthan about 100 Ω/sq, no greater than about 75 Ω/sq, no greater thanabout 50 Ω/sq, no greater than about 25 Ω/sq, no greater than about 15Ω/sq, no greater than about 10 Ω/sq, and down to about 1 Ω/sq or about0.1 Ω/sq, or less. At a transmittance of about 90% or greater, a sheetresistance can be no greater than about 500 Ω/sq, no greater than about400 Ω/sq, greater than about 350 Ω/sq, no greater than about 300 Ω/sq,no greater than about 200 Ω/sq, no greater than about 100 Ω/sq, nogreater than about 75 Ω/sq, no greater than about 50 Ω/sq, no greaterthan about 25 Ω/sq, no greater than about 15 Ω/sq, no greater than about10 Ω/sq, and down to about 1 Ω/sq or less. In some embodiments, a hostmaterial corresponds to a substrate with surface-embedded nanowires, andthe host material can be transparent or opaque, can be flexible orrigid, and can be composed of, for example, a polymer, an ionomer, EVA,TPO, TPU, PVB, PE, PET, PETG, polycarbonate, PVC, PP, acrylic-basedpolymer, ABS, ceramic, glass, or any combination thereof. In otherembodiments, a substrate can be transparent or opaque, can be flexibleor rigid, and can be composed of, for example, a polymer, an ionomer,EVA, TPO, TPU, PVB, PE, PET, PETG, polycarbonate, PVC, PP, acrylic-basedpolymer, ABS, ceramic, glass, or any combination thereof, where thesubstrate is coated with an electrically conductive material, insulator,or semiconductor (e.g., a doped metal oxide or an electricallyconductive polymer listed above) and with nanowires embedded into thecoating.

Certain surface-embedded device components can include additives ofeither, or both, MWCNT and SWCNT of average outer diameter in the rangeof about 1 nm to about 100 nm, about 1 nm to about 10 nm, about 10 nm toabout 50 nm, about 10 nm to about 80 nm, about 20 nm to about 80 nm, orabout 40 nm to about 60 nm, and an average length in the range of about50 nm to about 100 μm, about 100 nm to about 100 μm, about 500 nm to 50μm, about 5 μm to about 50 μm, about 5 μm to about 35 μm, about 25 μm toabout 80 μm, about 25 μm to about 50 μm, or about 25 μm to about 40 μm.A top of an embedding region can be located about 0.01 nm to about 100μm below a top, embedding surface of a host material, such as about 0.1nm to 100 μm below the embedding surface, about 0.1 nm to about 5 μmbelow the embedding surface, about 0.1 nm to about 3 μm below theembedding surface, about 0.1 nm to about 1 μm below the embeddingsurface, or about 0.1 nm to about 500 nm below the embedding surface.Nanotubes embedded into a host material can protrude from an embeddingsurface from about 0% by volume and up to about 90%, up to about 95%, orup to about 99% by volume. For example, in terms of a volume of ananotube exposed above the embedding surface relative to a total volumeof the nanotube (e.g., as defined relative to an outer diameter of ananotube), at least one nanotube can have an exposed volume percentage(or a population of the nanotubes can have an average exposed volumepercentage) of up to about 1%, up to about 5%, up to about 20%, up toabout 50%, or up to about 75% or about 95%. At a transmittance of about85% or greater (e.g., solar flux-weighted transmittance or one measuredat another range of optical wavelengths), a sheet resistance can be nogreater than about 500 Ω/sq, no greater than about 400 Ω/sq, no greaterthan about 350 Ω/sq, no greater than about 300 Ω/sq, no greater thanabout 200 Ω/sq, no greater than about 100 Ω/sq, no greater than about 75Ω/sq, no greater than about 50 Ω/sq, no greater than about 25 Ω/sq, nogreater than about 15 Ω/sq, no greater than about 10 Ω/sq, and down toabout 1 Ω/sq or less. At a transmittance of about 90% or greater, asheet resistance can be no greater than about 500 Ω/sq, no greater thanabout 400 Ω/sq, no greater than about 350 Ω/sq, no greater than about300 Ω/sq, on greater than about 200 Ω/sq, no greater than about 100Ω/sq, no greater than about 75 Ω/sq, no greater than about 50 Ω/sq, nogreater than about 25 Ω/sq, no greater than about 15 Ω/sq, no greaterthan about 10 Ω/sq, and down to about 1 Ω/sq or about 0.1 Ω/sq, or less.In some embodiments, a host material corresponds to a substrate withsurface-embedded nanotubes, and the host material can be transparent oropaque, can be flexible or rigid, and can be composed of, for example, apolymer, an ionomer, EVA, TPO, TPU, PVB, PE, PET, PETG, polycarbonate,PVC, PP, PMMA, glass, polyimide, epoxy, acrylic-based polymer, ABS,ceramic, glass, or any combination thereof. In other embodiments, asubstrate can be transparent or opaque, can be flexible or rigid, andcan be composed of, for example, a polymer, an ionomer, EVA, TPO, TPU,PVB, PE, PET, PETG, polycarbonate, PVC, PP, acrylic-based polymer, ABS,ceramic, glass, or any combination thereof, where the substrate iscoated with an electrically conductive material, insulator, orsemiconductor (e.g., a doped metal oxide or an electrically conductivepolymer listed above) and with nanotubes embedded into the coating.

Data obtained for surface-embedded device components reveals unexpectedfindings. For example, it was previously speculated that additivessuperficially deposited on top of a surface can yield greaterelectrically conductivity than additives physically embedded into a hostmaterial, since the host material (which is an insulator) was speculatedto inhibit conducting ability of the additives. However, andunexpectedly, improved, electrical conductivity was observed forsurface-embedded structures, supporting the notion of favorable junctionformation and network-to-bulk transition imposed by embedding theadditives within a host material.

Devices Including Surface-Embedded Additives

The surface-embedded device components described herein can beincorporated in a variety of devices, including solar devices, solarglass, low iron glasses, smart windows, displays, organic light-emittingdiodes (or OLEDs), architectural glasses, aircraft windshields,electrochromic devices, multichromic devices, as well as otherelectronic and optoelectronic devices.

In some embodiments, the surface-embedded device components can beincorporated in solar devices. During operation of a solar device,sunlight is absorbed by a photoactive material to produce chargecarriers in the form of electron-hole pairs. Electrons exit thephotoactive material through one electrode, while holes exit thephotoactive material through another electrode. The net effect is a flowof an electric current through the solar device driven by incidentsunlight, which electric current can be delivered to an external load toperform useful work. Solar devices include single junction solar cells,multi-junction or tandem solar cells, thin-film solar cells,dye-sensitized solar cells, excitonic solar cells, quantum dot solarcells, and bulk heterojunction solar cells. Photoactive materials usedin these solar devices can be organic, inorganic, composite, hybrid, ora combination thereof. Examples of solar cells include those based onmonocrystalline silicon; polycrystalline silicon; microcrystallinesilicon; nanocrystalline silicon; amorphous silicon; thin-film silicon;monocrystalline, polycrystalline, microcrystalline, nanocrystalline, andthin-film forms of other semiconductor materials such as germanium,gallium arsenide, copper indium gallium selenide (or CIGS), copperindium selenide, cadium telluride (or CdTe), and gallium indiumphosphide; polymers (e.g., electrically conductive or semiconductingpolymers); bicontinuous polymer-fullerene composites; thin-filmphotoactive materials, and combinations thereof.

FIG. 6 illustrates a solar device 600 according to an embodiment of theinvention. The solar device 600 includes a photoactive layer 610 formedof a set of photoactive materials and disposed between a set of frontdevice layers and a set of back device layers. In certain cases, variouslayers are built up from a front sheet (glass), in which case the frontsheet can be described as a superstrate. Although various device layersare illustrated and explained as follows, it should be understood thatcertain of these device layers can be omitted, combined, furthersub-divided, or reordered, and additional device layers can be includedin accordance with other embodiments.

Referring to FIG. 6, the front device layers include: (1) a front cover602 formed of a glass (or another ceramic), a fluoropolymer (e.g.,polytetrafluoroethylene (or PTFE), polyvinylidene fluoride (or PVDF),fluorinated ethylene propylene (or FEP), or ethylene tetrafluoroethylene(or ETFE)), another suitable material that is substantially transparentto incident sunlight, or any combination thereof; (2) an encapsulantlayer 604 adjacent to the front cover 602 and implemented as a barrierfilm formed of ethylene vinyl acetate (or EVA) (e.g., available asDuPont™ Elvax®), polyvinyl butaryl (or PVB) (e.g., available as DuPont™Butacite®), polyvinyl alcohol (or PVA), silicone, polysiloxane, anionomer (e.g., available as SentryGlas®), acrylic-based polymer,polymethyl methacrylate (or PMMA), TPU, TPO, another suitableencapsulant material, or any combination thereof; (3) a set of bus barsor metallizations 618 at least partially covered by and extendingthrough the encapsulant layer 604 and formed of a metal (e.g., n-typeAg, Ag ink, or Ag paste), a metal alloy, another suitable electricallyconductive material, or any combination thereof; (4) an anti-reflectioncoating 606 (or ARC) adjacent to the encapsulant layer 604; and (5) afront electrode 608 disposed between the anti-reflection coating 606 andthe photoactive layer 610 and formed of a doped metal oxide (e.g.,indium tin oxide), another suitable electrically conductive materialthat is substantially transparent to incident sunlight, or anycombination thereof.

The back device layers include: (1) a substrate 614 formed of silicon,polyimide, (e.g., poly(4,4′-oxydiphenylene-pyromellitimide) available asDuPont® Kapton®), polyethylene naphthalate (or PEN) (e.g., available asTeonex®), polyester available as Melinex® ST polyester), glass,aluminum, stainless steel, another suitable substrate material, or anycombination thereof; (2) a back electrode 612 disposed between thephotoactive layer 610 and the substrate 614 and formed of a metal, ametal alloy, another suitable electrically conductive material, or anycombination thereof; (3) an encapsulant layer 616 adjacent to thesubstrate 614 and implemented as a barrier film formed of ethylene vinylacetate (or EVA) (e.g., available as DuPont™ Elvax®), polyvinyl butaryl(or PVB) (e.g., available as DuPont™ Butacite®), polyvinyl alcohol (orPVA), silicone, polysiloxane, oo ionomer (e.g., available asSentryGlas®), acrylic-based polymer, polymethyl methacrylate (PMMA),TPO, TPU, another suitable encapsulant material, or any combinationthereof; and (4) a back cover 620 formed of a glass (or anotherceramic), a fluoropolymer (e.g., polyvinyl fluoride (or PVF)), apolyester (e.g., biaxially-oriented polyethylene terephthalate (or PET)available as Mylar®, Melinex®, and Teijin® Tetoron®), another suitablematerial, or any combination thereof. Various other combinations andordering of the front and back device layers are contemplated. In someembodiments, for example, the back cover 620 can serve as a substrate ontop of which other device layers are disposed, such as a set of bus barsor other metallization and an encapsulant layer.

In general, any one or more of the device layers of the solar device 600can be implemented as the surface-embedded device components describedherein, such as those illustrated in FIG. 1D through FIG. 1I and FIG. 2Athrough FIG. 2H.

The purpose of the encapsulant layers 604 and 616 is to provide thesolar device 600 with structural support, electrical isolation, physicalisolation, thermal conduction, and barrier properties. In someembodiments, either, or both, of the encapsulant layers 604 and 616 caninclude surface-embedded additives to impart additional or enhancedfunctionality such as electrical conductivity, thermal conductivity,spectral shifting, and absorption enhancement. It is also contemplatedthat either, or both, of the encapsulant layers 604 and 616 can includeadditives that are incorporated, in another suitable fashion, such asthrough bulk incorporation of additives to impart electricalconductivity or other desired functionality.

For example, the sun-facing, encapsulant layer 604 can besurface-embedded, with a down-shifting phosphor, and the encapsulantlayer 616 can be surface-embedded with an up-shifting phosphor, yieldingthe solar device 600 that tunes an incident radiation spectrum from boththe infrared range to the visible range and from the ultraviolet rangeto the visible range. Instead of the visible range, the incidentradiation spectrum can be tuned to another suitable range of wavelengthsmatched to a bandgap energy of the photoactive layer 610.

Alternatively, or in conjunction, either, or both, of the encapsulantlayers 604 and 616 can be surface-embedded with electrically conductiveadditives. Such electrically conductive encapsulant layers 604 and 616can operate in conjunction with the front electrode 608 and the backelectrode 612, or can replace the front electrode 608 and the backelectrode 612 altogether, such that separate or dedicated electrodes canbe omitted from the solar device 600.

Electrically conductive additives (which are surface embedded in theencapsulant layers 604 and 616 or another set of device layers of thesolar device 600) can be in electrical contact with, or otherwiseelectrically connected to, the photoactive layer 610. In someembodiments, the photoactive layer 610 can include a buffer layer, andelectrically conductive additives can be in electrical contact with, orotherwise electrically connected to, the buffer layer of the photoactivelayer 610. A buffer layer (which can also be referred as ananti-shunting layer or a shunting resistance layer) can serve toincrease or otherwise modify a shunt resistance of solar devices, suchas those with a shunt resistance below about 500 Ω·cm². Low shuntresistance sometimes can occur because of physical defects (e.g.,omission of photoactive material), poorly grown material with areas ofhigh conductivity, or a combination thereof. Low shunt resistance cansometimes lead to high dark current and, thus, low Fill Factor and lowopen circuit voltage. A buffer layer can be implemented as a thininsulating or resistive layer to inhibit leakage of current in anundesired direction. When a solar device is illuminated, a resultingvoltage generated can be sufficient to tunnel charge carriers throughthe buffer layer, with little or moderate increase in series resistance.Examples of buffer layers include CdS layers in CIGS and CdTe solardevices, ZnO(i) layers placed between CdS and ZnO:Al layers in CIGSsolar devices, and ZnO(i) or SnO₂ layers in CdTe solar devices. Otherpurposes of the ZnO(i) layers include resistance against sputteringdamage during deposition of the ZnO:Al layers. Additional examples ofbuffer layers include SiO₂ or Si₃N₄ passivization layers in siliconsolar cells that inhibit surface carrier recombination. In the case ofphysical defects, additives, such as in the form of nanowires, canbridge over those defects. The additives also can be in electricalcontact with or otherwise electrically connected to, a transparent metaloxide layer or another electrically conductive layer that provides workfunction matching. It is also contemplated that a buffer layer can beimplemented as a separate layer with respect to the photoactive layer610, and electrically conductive additives can be in electrical contactwith, or otherwise electrically connected to, such separate bufferlayer.

Alternatively, or in conjunction, either, or both, of the encapsulantlayers 604 and 616 can be surface-embedded with additives to provideUV-resistance or otherwise provide protection againstphotodecomposition, thermal degradation, photochemical degradation, orphotothermal degradation. Light of wavelengths below 380 nm can generatefree radicals, such as hydroperoxides and peroxides, which in thepresence of oxygen can lead to cross-linking or scission of polymerchains. Small molecules, double carbon-carbon bonds, discoloring,yellowing, browning, transmittance loss, generation of gases fromphotothermal degradation, delamination of an encapsulant material from asubstrate, mismatching of neighboring solar cells in a solar module, andloss in system power output are possible results of the generation offree radicals. In some embodiments, either, or both, of the encapsulantlayers 604 and 616 can be surface-embedded with UV absorbers2-hydroxy-4-n-octyloxybenzophenone available as Cyasorb UV 531™, UVlight stabilizers (e.g., benzophenone andbis(2,2,6,6-tetramethyl-4-piperidinyl)sebacate available as Tinuvin770), antioxidants (e.g., tris(mono-nonylphenyl)phosphite available asNaugard P), or any combination thereof. The localization of additives,such as UV stabilizers, within an embedding region adjacent to asun-facing or top surface of the encapsulant layer 604 allowssubstantially complete UV stabilization before harmful UV radiation canbe transmitted through a bulk of the encapsulant layer 604, providingenhanced UV stabilization to the encapsulant layer 604 as well as devicelayers below the encapsulant layer 604. In some embodiments,surface-embedding of a down-shifting phosphor can provide such UVstabilization function by converting radiation from the ultravioletrange to the visible range before transmission through various layers ofthe solar device 600.

Other types of additives can be surface-embedded into either, or both,of the encapsulant layers 604 and 616 (or a base copolymer or otherprecursor of the encapsulant layers 604 and 616), such as cross-linkingpromoters (e.g., organic peroxides), initiators, primers, and curingagents (e.g., OO-t-butyl-O-(2-ethylhexyl)monoperoxycarbonate availableas Lupersol TBEC) to promote curing or other processing of theencapsulant layers 604 and 616. Desiccants can be surface-embedded toprovide improved moisture barrier characteristics, and ceramics or othertypes of materials can be surface-embedded to provide improved oxygenbarrier characteristics. Additives formed of an electrically conductivematerial or a semiconductor also can be surface-embedded to adjust awork function or to distribute heat more efficiently and evenly acrossthe solar device 600. In addition, additives can be surface-embedded andlocalized within an embedding region adjacent to and facing thephotoactive layer 610 to induce absorption of light of a desiredwavelength range by the photoactive layer 610, such as by one or more ofscattering, plasmonic, and polaritonic effects. Examples of suitableabsorption-inducing additives include Ag nanoparticles, Ag nanoparticlesencapsulated in a semiconductor (e.g., core-shell nanoparticles with asilver core and a silicon shell), Ag nanoparticles encapsulated in aninsulator (e.g., core-shell nanoparticles with a silver core and aninsulator shell), Ag nanowires, Ag nanowires encapsulated in asemiconductor (e.g., core-shell nanowires with a silver core and asilicon shell), Ag nanowires encapsulated in an insulator (e.g.,core-shell nanowires with a silver core and an insulator shell),nanoparticles of other metals, nanowires of other metals, porousnanoparticles, porous nanowires, nanoporous materials, nanoporousglasses (or other ceramics), nanoporous semiconductors, and so forth.

Other device layers of the solar device 600 can be surface-embedded withadditives in place of, or in combination with, the encapsulant layers604 and 616, and the preceding discussion with respect to theencapsulant layers 604 and 616 is also applicable with respect to theother device layers. In some embodiments, either, or both, of the frontcover 602 and the back cover 620 can include surface-embedded additivesto impart additional or enhanced functionality such as electricalconductivity, thermal conductivity, spectral shifting, and absorptionenhancement. For example, the front cover 602 can be surface-embeddedwith a down-shifting phosphor to tune an incident radiation spectrum orprovide an UV stabilization function. As another example, the substrate614 can be surface-embedded with electrically conductive additives, andcan operate in conjunction with, or replace, the back electrode 612.

Through the incorporation of surface-embedded additives, the solardevice 600 can operate with an improved solar power conversionefficiency, which can be expressed as V_(oc)×J_(sc)×FF/P_(AM1.5), whereV_(oc) corresponds to an open circuit voltage, J_(sc) corresponds to ashort circuit current, FF is the fill factor, and P_(AM1.5) is theincident power per unit area from the AM1.5 solar spectrum. By impartingimproved electrical conductivity to one or more layers of the solardevice 600, the solar power conversion efficiency can be increased byincreasing the Fill Factor and J_(sc). By imparting improvedtransparency to one or more layers of the solar device 600, the solarpower conversion efficiency can be increased by increasing J_(sc). Byimparting improved absorption through the incorporation ofabsorption-inducing additives, the solar power conversion efficiency canbe increased by increasing J_(sc). And, by providing enhancedutilization of a solar spectrum through the incorporation of spectralshifting additives, the solar power conversion efficiency can beincreased by increasing J_(sc). Down-shifting can be useful for certainthin-film solar devices, such as CIGS and CdTe solar devices, which usea CdS buffer layer that can absorb blue light. In such devices,down-shifting can reduce or prevent the CdS layer from causing unwantedabsorption, thereby directly leading to an increase in J_(sc) as well asindirectly improving the Fill Factor and V_(oc) by allowing thicker CdSlayers that can increase shunt resistance. In some embodiments, thesolar power conversion efficiency can be at least about 10%, such as atleast about 12%, at least about 15%, at least about 18%, at least about20%, or at least about 25%, and up to about 30%, up to about 40%, up toabout 50%, or more.

FIG. 7 illustrates a solar device 700 according to another embodiment ofthe invention. Certain aspects of the solar device 700 can beimplemented in a similar fashion as explained above for the solar device600, and those aspects need not be repeated below. Also, althoughvarious device layers are illustrated and explained as follows, itshould be understood that certain of these device layers can be omitted,combined, further sub-divided, or reordered, and additional devicelayers can be included in accordance with other embodiments.

As illustrated in FIG. 7, the solar device 700 is a multi-junction solarcell, including multiple photoactive layers 708 and 716 having differentbandgap energies, namely E_(g1) and E_(g2), respectively, and whereE_(g1)>E_(g2). While the two photoactive layers 708 and 716 areillustrated in FIG. 7, it is contemplated that three or more photoactivelayers can be included in the solar device 700. The photoactive layer708 is disposed between a pair of electrodes 706 and 710, and thephotoactive layer 716 is disposed between a pair of electrodes 714 and718. In the illustrated embodiment, the solar device 700 includesmultiple encapsulant layers 704, 712, and 720, with the encapsulantlayer 704 disposed between a front cover 702 and the electrode 706, theencapsulant layer 712 disposed between the electrodes 710 and 714, andthe encapsulant layer 720 disposed between the electrode 718 and a backcover 722.

In general, any one or more of the device layers of the solar device 700can be implemented as the surface-embedded device components describedherein, such as those illustrated in FIG. 1D through FIG. 1I and FIG. 2Athrough FIG. 2H.

In some embodiments, one or more of the encapsulant layers 704, 712, and720 can include surface-embedded additives to impart functionality suchas electrical conductivity, thermal conductivity, spectral shifting, andabsorption enhancement. It is also contemplated that additives can beincorporated in another suitable fashion, such as through bulkincorporation of additives to impart electrical conductivity or otherdesired functionality.

For example, the encapsulant layer 704 can be surface-embedded with aphosphor that performs down-shifting with respect to E_(g1), theencapsulant layer 712 can be surface-embedded with another phosphor thatperforms down-shifting with respect to E_(g2), and the encapsulant layer720 can be surface-embedded with yet another phosphor that performsup-shifting with respect to E_(g1) or E_(g2). During operation of thesolar device 700, incident solar radiation strikes the encapsulant layer704, which performs down-shifting of higher energy radiation to matchE_(g1) of the photoactive layer 708. Solar radiation with energies lowerthan E_(g1) passes through the photoactive layer 708 and strikes theencapsulant layer 712, which performs down-shifting of higher energyradiation to match E_(g2) of the photoactive layer 716. Solar radiationwith energies lower than E_(g2) passes through the photoactive layer 716and strikes the encapsulant layer 720, which performs up-shifting tomatch E_(g1) or E_(g2). By operating in such manner, the solar device700 provides enhanced utilization of a solar spectrum, by allowingdifferent energy bands within the solar spectrum to be efficientlycollected and converted into electricity.

FIG. 8 illustrates a solar device 800 according to another embodiment ofthe invention. Certain aspects of the solar device 800 can beimplemented in a similar fashion as explained above for the solardevices 600 and 700, and those aspects need not be repeated below. Also,although various device layers are illustrated and explained as follows,it should be understood that certain of these device layers can beomitted, combined, further sub-divided, or reordered, and additionaldevice layers can be included in accordance with other embodiments.

As illustrated in FIG. 8, the solar device 800 includes a photovoltaiccell 802, which is a p-n junction device formed of crystalline siliconor another suitable photoactive material. The solar device 800 alsoincludes a luminescent solar concentrator (or ESC) 804, which is formedas a waveguide slab that is adjacent and optically connected to thephotovoltaic cell 802. Although the single photovoltaic cell 802 isillustrated in FIG. 8, it is contemplated that multiple photovoltaiccells can be included at various edges of the LSC 804. The LSC 804includes an encapsulant layer 808 (or other interlayer) that is disposedbetween a front cover 806 and a back cover 810.

In general, any one or more of the device layers of the LSC 804 can beimplemented as the surface-embedded device components described herein,such as those illustrated in FIG. 1D through FIG. 1I and FIG. 2A throughFIG. 2H. In the illustrated embodiment, the encapsulant layer 808 issurface-embedded with a set of phosphors. In some embodiments, aphosphor can be surface-embedded and localized within an embeddingregion adjacent to a sun-facing or top surface of the encapsulant layer808, although the localization of the phosphor can be varied for otherembodiments. During operation of the solar device 800, the LSC 804captures a solar spectrum across a wide range of angles of incidencewith a surface-embedded phosphor, and the phosphor emits light withinthe encapsulant layer 808 at a different wavelength (or a differentrange of wavelengths) and, in combination with total internalreflection, concentrates the light that is guided towards the edges ofthe encapsulant layer 808. The energy difference between absorption andthe emitted light reduces instances of self-absorption by the phosphor.In such fashion, the LSC 804 can achieve high optical concentrationswithout requiring solar tracking. The resulting emitted light intensitycan concentrate sunlight by a factor of about 5 or more, such as by afactor of at least about 10, at least about 20, or at least about 30,and up to about 40 or more, and, when directed onto the photovoltaiccell 802, the LSC 804 can increase a solar power conversion efficiencyby a factor in the range of about 2 to about 10 (or more).

Surface-embedding allows a phosphor to be controllably embedded into asurface of a polymer or another encapsulant material, with highuniformity and with little or no agglomeration that can otherwise leadto self-quenching of emission and hence reduced quantum efficiency.Also, surface-embedding addresses issues of delamination andinefficiencies and other losses resulting from light absorption.Embedded phosphor species buried directly into a surface of a polymer oranother encapsulant material can convert incident light substantiallyimmediately at an interface, forming a highly efficient configurationfor a wavelength-conversion solar device.

In other embodiments, the surface-embedded device components describedherein can be incorporated in smart windows. FIG. 9 illustrates a smartwindow 900 according to an embodiment of the invention. Certain aspectsof the smart window 900 can be implemented in a similar fashion asexplained above for the solar devices 600, 700, and 800, and thoseaspects need not be repeated below. Also, although various device layersare illustrated, and explained as follows, it should be understood thatcertain of these device layers can be omitted, combined, furthersub-divided, or reordered, and additional device layers can be includedin accordance with other embodiments.

As illustrated in FIG. 9, the smart window 900 includes a front cover902 and a back cover 906, between which is an encapsulant layer 904 (orother interlayer) that controls passage of light through the smartwindow 900. In general, any one or more of the device layers of thesmart window 900 can be implemented as the surface-embedded devicecomponents described herein, such as those illustrated in FIG. 1Dthrough FIG. 1I and FIG. 2A through FIG. 2H. In the illustratedembodiment, the encapsulant layer 904 is surface-embedded with a set ofadditives, such as in the fashion illustrated in FIG. 2H, although thelocalization and type of additives can be varied for other embodiments.For example, the encapsulant layer 904 can be surface-embedded withelectrochromic additives. When an electric field is applied, theelectrochromic additives can respond by undergoing a color change or achange in shade. When the electrical field is absent, the electrochromicadditives can revert back to its initial color or shade. In such manner,the smart window 900 can appear transparent or translucent. Other typesof multichromic additives can be used in place of, or in combinationwith, electrochromic additives. Alternatively, or in conjunction, theencapsulant layer 904 can be surface-embedded with electricallyconductive additives to serve as electrodes through which an electricfield can be applied.

In still other embodiments, the surface-embedded device componentsdescribed herein can be incorporated in display devices, such as flatpanel displays, liquid crystal displays (“LCDs”), plasma displays, OLEDdisplays, electronic-paper, quantum dot displays, and flexible displays,FIG. 10 illustrates a LCD 1000 according to an embodiment of theinvention. Certain aspects of the LCD 1000 can be implemented in asimilar fashion as explained above for the solar devices 600, 700, and800 and the smart window 900, and those aspects need not be repeatedbelow. Also, although various device layers are illustrated andexplained as follows, it should be understood that certain of thesedevice layers can be omitted, combined, further sub-divided, orreordered, and additional device layers can be included in accordancewith other embodiments.

As illustrated in FIG. 10, the LCD 1000 is a light-emitting diode(“LED”)-backlight LCD and includes an array of LEDs 1002 (or anotherlight source) that is adjacent and optically connected to a backlightmodule 1006, which, in turn, is adjacent and optically connected to aLCD module 1004. The backlight module 1006 includes a front cover 1008and a back cover 1012, between which is an encapsulant layer 1010 (orother interlayer). In general, any one or more of the device layers ofthe backlight module 1006 can be implemented as the surface-embeddeddevice components described herein, such as those illustrated in FIG. 1Dthrough FIG. 1I and FIG. 2A through FIG. 2H. In the illustratedembodiment, the LEDs 1002 emit light of a particular color, such as bluelight, and the backlight module 1006 includes a set of surface-embeddedphosphors that absorb the blue light and emit light of different colors,such as red light and green light, in some embodiments, the phosphorscan be surface-embedded and localized within an embedding regionadjacent to an edge of the encapsulant layer 1010 facing the LEDs 1002,although the localization of the phosphors can be varied for otherembodiments. A combination of the blue light emitted by the LEDs 1002and the red light and green light emitted by the phosphors within thebacklight module 1006 appear as “white” light, which is directed by thebacklight module 1006 towards the LCD module 1004. In addition to thephosphors, a diffuser can be surface-embedded, bulk incorporated, orotherwise included within the encapsulant layer 1010 to spread out orotherwise scatter light towards the LCD module 1004. Alternatively, orin conjunction, such a diffuser can be surface-embedded, bulkincorporated, or otherwise included within either, or both, of the fromcover 1008 and the back cover 1012. Examples of suitable diffusersinclude nano-sized or micron-sized particles formed of a ceramic (e.g.,titania or silica), a metal (e.g., silver), or another suitablematerial.

FIG. 12 are schematics of a number of electronic device architecturesrepresenting different types of touch sensors and displays according toan embodiment of the invention. In these schematics, an ITO electrode(patterned, and/or unpatterened) is deposited on a hardcoat, film,and/or glass. In all cases where there is an OCA adjacent to an ITOelectrode, instead of using ITO (patterned and/or unpatterned) depositedon a hardcoat, film, and/or glass, an electrode can be surface-embeddedinto the OCA. Certain aspects of the devices of FIG. 12 can beimplemented in a similar fashion as explained above, and those aspectsneed not be repeated. Also, although various device layers areillustrated, it should be understood that certain of these device layerscan be omitted, combined, further sub-divided, or reordered, andadditional device layers can be included in accordance with otherembodiments.

Manufacturing Methods of Surface-Embedded Device Components

Disclosed herein are manufacturing methods to form surface-embeddeddevice components in a highly-scalable, rapid, and low-cost fashion, inwhich additives are durably and surface-embedded into a wide variety ofhost materials, securely burrowing the additives into the hostmaterials.

Some embodiments of the manufacturing methods can be generallyclassified into two categories: (1) surface-embedding additives into adry composition to yield a host material with the surface-embeddedadditives; and (2) surface-embedding additives into a wet composition toyield a host material with the surface-embedded additives. It will beunderstood that such classification is for ease of presentation, andthat “dry” and “wet” can be viewed as relative terms (e.g., with varyingdegrees of dryness or wetness), and that the manufacturing methods canapply to a continuum spanned between fully “dry” and fully “wet”.Accordingly, processing conditions and materials described with respectto one category (e.g., dry composition) can also apply with respect toanother category (e.g., wet composition), and vice versa. It will alsobe understood that hybrids or combinations of the two categories arecontemplated, such as where a wet composition is dried or otherwiseconverted into a dry composition, followed by surface-embedding ofadditives into the dry composition to yield a host material with thesurface-embedded additives. It will further be understood that, although“dry” and “wet” sometimes may refer to a level of water content or alevel of solvent content, “dry” and “wet” also may refer to anothercharacteristic of a composition in other instances, such as a degree ofcross-linking or polymerization.

Advantageously, some embodiments of the manufacturing methods can becarried out under moderate conditions of temperature and pressure (e.g.,room temperature and pressure conditions) and can be implemented in aroll-to-roll fashion, thereby facilitating integration in a devicemanufacturing line. Also, some embodiments of the manufacturing methodscan be applied to a polymer extrusion manufacturing setting. For exampleand by way of preview, silver nanowires (or another type of additive)can be suspended in an embedding fluid, and can be sprayed onto anextrudate, where the embedding fluid facilitates embedding of the silvernanowires into the extrudate. The extrudate can be hot, molten, soft, orotherwise in a state that allows embedding of the silver nanowires inthe presence of the embedding fluid. The resulting nanowire-embeddedextrudate can be combined with another extrudate (either with or withoutembedded additives) via co-extrusion, where two or more materials areextruded through a die with two or more orifices arranged such that theextrudates merge and weld together in a laminar structure beforecooling. The materials can be fed to the die from separate extruders.Co-extrusion has benefits, for example, in the case of an encapsulantlayer for a solar device that incorporates multiple layers withrespective or different functionality, such as in terms of permeabilityto oxygen, carbon dioxide, and water vapor; electrical conductivity;thermal conductivity; spectral shifting; and so forth.

Attention first turns to FIG. 5A and FIG. 5B, which illustratemanufacturing methods for surface-embedding additives into drycompositions, according to embodiments of the invention.

By way of overview, the illustrated embodiments involve the applicationof an embedding fluid to allow additives to be embedded into a drycomposition, such as one including a polymer, a ceramic, a ceramicprecursor, or a combination thereof. In general, the embedding fluidserves to reversibly alter the state of the dry composition, such as bydissolving, reacting, softening, solvating, swelling, or any combinationthereof, thereby facilitating embedding of the additives into the drycomposition. For example, the embedding fluid can be speciallyformulated to act as an effective solvent for a polymer, while possiblyalso being modified with stabilizers (e.g., dispersants) to help suspendthe additives in the embedding fluid. The embedding fluid also can bespecially formulated to reduce or eliminate problems withsolvent/polymer interaction, such as hazing, crazing, and blushing. Theembedding fluid can include a solvent or a solvent mixture that isoptimized to be low-cost, Volatile Organic Compound (“VOC”)-free,VOC-exempt or low-VOC, Hazardous Air Pollutant (“HAP”)-free, non-ozonedepleting substances (“non-ODS”), low volatility or non-volatile, andlow hazard or non-hazardous. As another example, the dry composition caninclude a ceramic or a ceramic precursor in the form of a gel or asemisolid, and application of the embedding fluid can cause the gel tobe swollen by filling pores with the fluid, by elongation of partiallyuncondensed oligomeric or polymeric chains, or both. As a furtherexample, the dry composition can include a ceramic or a ceramicprecursor in the form of an ionic polymer, such as sodium silicate oranother alkali metal silicate, and application of the embedding fluidcan dissolve at least a portion of the ionic polymer to allow embeddingof the additives. The embedding of the additives is then followed byhardening or other change in state of the softened or swelledcomposition, resulting in a host material having the additives embeddedtherein. For example, the softened or swelled composition can behardened by exposure to ambient conditions, or by cooling the softenedor swelled composition. In other embodiments, the softened or swelledcomposition is hardened by evaporating or otherwise removing at least aportion of the embedding fluid (or other liquid or liquid phase that ispresent), applying airflow, applying a vacuum, or any combinationthereof. In the case of a ceramic precursor, curing can be carried outafter embedding such that the ceramic precursor is converted into aglass. Curing can be omitted, depending on the particular application.Depending on the particular ceramic precursor (e.g., a silane), more orless heat can be involved to achieve various degrees of curing orconversion into a fully reacted or fully formed glass.

In some embodiments, the mechanism of action of surface-embedding can bebroken down into stages, as an aid for conceptualization and for ease ofpresentation. However, these stages can be combined, or can occursubstantially simultaneously. These stages include: (a) the embeddingfluid interacting with a surface (here, for example, a surface of apolymer), (b) the additives penetrating the surface, and (c) theembedding fluid leaving the surface. It should be understood that themechanism of action can differ for other embodiments.

In stage (a) and as the embedding fluid impacts the surface, polymerchains of the dry composition disentangle and extend up and above thesurface and occupy a larger volume due to a combination of swelling andsolvation, which loosen the polymer chains. The zone of swollen polymerextends above and below the original surface of the dry composition.This effect occurs over the span of a few seconds or less, which issurprisingly quick given that typical solvent/polymer dissolutionprocedures are carried out in terms of hours and days. The surface ofthe polymer has a higher concentration of low molecular weight chains,chain ends, and high surface energy functionality compared to the bulk,which can increase the rate of swelling or solubilizing at the surface.

In stage (b) and once the polymer surface has been swollen, additivesare applied into this zone between the polymer chains by the momentum ofthe embedding fluid and the additives (or by other application ofvelocity to the additives or the embedding fluid) and bydiffusion/mixing processes as the embedding fluid impacts the surface.In some embodiments, embedding can be achieved without the momentum ofthe embedding fluid and the additives. Another factor that can affectthis swelling/dispersion process is the impact energy—if the additivesimpact the surface, the momentum transfer in a highly localized area canimpart energy input into the surface, which can heat the surface toincrease solubility of the polymer, thereby facilitating the secureembedding, surface-impregnation, or partial sinking of the additivesinto the polymer.

In stage (c) and as the embedding fluid evaporates or is otherwiseremoved, the polymer chains re-form with one another and around theadditives. The polymer chains that had extended above and beyond theoriginal surface can capture and adsorb the additives, and pull theminto the surface, rendering them securely and durably embedded therein.The structural perturbations due to the embedded additives can berelatively small, and the resulting host material and its embeddedadditives can substantially retain their original characteristics suchas optical transparency and surface morphology.

Referring to FIG. 5A, a dry composition 500 is provided in the form of asheet, a film, or other suitable form. The dry composition 500 cancorrespond to a host material and, in particular, can include anymaterial previously listed as suitable host materials, such as apolymer, a ceramic, or any combination thereof. It is also contemplatedthat the dry composition 500 can correspond to a host materialprecursor, which can be converted into the host material by suitableprocessing, such as drying, curing, cross-linking, polymerizing, or anycombination thereof. In some embodiments, the dry composition 500 caninclude a material with a solid phase as well as a liquid phase, or caninclude a material that is at least partially solid or has propertiesresembling those of a solid, such as a semisolid, a gel, and the like.Next, and referring to FIG. 5A, additives 502 and an embedding fluid 504are applied to the dry composition 500. The additives 502 can be insolution or otherwise dispersed in the embedding fluid 504, and can besimultaneously applied to the dry composition 500 via one-stepembedding. Alternatively, the additives 502 can be separately applied tothe dry composition 500 before, during, or after the embedding fluid 504treats the dry composition 500. The separate application of theadditives 502 can be referred as two-step embedding. Subsequently, theresulting host material 506 has at least some of the additives 502partially or fully embedded into a surface of the host material 506.Optionally, suitable processing can be carried out to convert thesoftened or swelled composition 500 into the host material 506. Duringdevice assembly, the host material 506 with the embedded additives 502can be laminated or otherwise connected to adjacent device layers, orcan serve as a substrate onto which adjacent device layers are formed,laminated, or otherwise applied.

FIG. 5B is a process flow similar to FIG. 5A, but with a dry composition508 provided in the form of a coating that is disposed on top of asubstrate 510. The dry composition 508 can correspond to a hostmaterial, or can correspond to a host material precursor, which can beconverted into the host material by suitable processing, such as drying,curing, cross-linking, polymerizing, or any combination thereof. Othercharacteristics of the dry composition 508 can be similar to thosedescribed above with reference to FIG. 5A, and are not repeated below.Referring to FIG. 5B, the substrate 510 can be transparent or opaque,can be flexible or rigid, and can be composed of, for example, apolymer, an ionomer, EVA, PVB, TPO, TPU, PE, PET, PETG, polycarbonate,PVC, PP, acrylic-based polymer, ABS, ceramic, glass, or any combinationthereof, as well as any other material previously listed as suitablehost materials. The substrate 510 can serve as a temporary substratethat is subsequently removed during device assembly, or can be retainedin a resulting device as a layer or other component of the device. Next,additives 512 and an embedding fluid 514 are applied to the drycomposition 508. The additives 512 can be in solution or otherwisedispersed in the embedding fluid 514, and can be simultaneously appliedto the dry composition 508 via one-step embedding. Alternatively, theadditives 512 can be separately applied to the dry composition 508before, during, or after the embedding fluid 514 treats the drycomposition 508. As noted above, the separate application of theadditives 512 can be referred as two-step embedding. Subsequently, theresulting host material 516 (which is disposed on top of the substrate510) has at least some of the additives 512 partially or fully embeddedinto a surface of the host material 516. Optionally, suitable processingcan be carried out to convert the softened or swelled composition 508into the host material 516. During device assembly, the host material516 with the embedded additives 512 can be laminated or otherwiseconnected to adjacent device layers, or can serve as a substrate ontowhich adjacent device layers are formed, laminated, or otherwiseapplied.

In some embodiments, additives are dispersed in an embedding fluid, ordispersed in a separate carrier fluid and separately applied to a drycomposition. Dispersion can be accomplished by mixing, milling,sonicating, shaking, vibrating, flowing, chemically modifying theadditives' surfaces, chemically modifying a fluid, adding a dispersingor suspending agent to the fluid, or otherwise processing the additivesto achieve the desired dispersion. The dispersion can be uniform ornon-uniform. A carrier fluid can serve as an embedding fluid (e.g., anadditional embedding fluid), or can have similar characteristics as anembedding fluid. In other embodiments, a carrier fluid can serve as atransport medium to carry or convey additives, but is otherwisesubstantially inert towards the additives and the dry composition.

Fluids (e.g., embedding fluids and carrier fluids) can include liquids,gases, or supercritical fluids. Combinations of different types offluids are also suitable. Fluids can include one or more solvents. Forexample, a fluid can include water, an ionic or ion-containing solution,an organic solvent (e.g., a polar, organic solvent; a non-polar, organicsolvent; an aprotic solvent; a protic solvent; a polar aprotic solvent,or, a polar, protic solvent); an inorganic solvent, or any combinationthereof. Oils also can be considered suitable fluids. Salts,surfactants, dispersants, stabilizers, or binders can also be includedin the fluids.

Examples of suitable organic solvents include 2-methyltetrahydrofuran, achloro-hydrocarbon, a fluoro-hydrocarbon, a ketone, a paraffin,acetaldehyde, acetic acid, acetic anhydride, acetone, acetonitrile, onalkyne, an olefin, aniline, benzene, benzonitrile, benzyl alcohol,benzyl ether, butanol, butanone, butyl acetate, butyl ether, butylformate, butyraldehyde, butyric acid, butyronitrile, carbon disulfide,carbon tetrachloride, chlorobenzene, chlorobutane, chloroform,cycloaliphatic hydrocarbons, cyclohexane, cyclohexanol, cyclohexanone,cyclopentanone, cyclopentyl methyl ether, diacetone alcohol,dichloroethane, dichloromethane, diethyl carbonate, diethyl ether,diethylene glycol, diglyme, di-isopropylamine, dimethoxyethane, dimethylformamide, dimethyl sulfoxide, dimethylamine, dimethylbutane,dimethylether, dimethylformamide, dimethylpentane, dimethylsulfoxide,dioxane, dodecafluoro-1-hepatanol, ethanol, ethyl acetate, ethyl ether,ethyl formate, ethyl propionate, ethylene dichloride, ethylene glycol,formamide, formic acid, glycerine, heptane, hexafluoroisopropanol,hexamethylphosphoramide, hexamethylphosphorous triamide, hexane,hexanone, hydrogen peroxide, hypochlorite, butyl acetate, i-butylalcohol, i-butyl formate, i-butylamine, i-octane, propyl acetate,i-propyl ether, isopropanol, isopropylamine, ketone peroxide, methanoland calcium chloride solution, methanol, methoxyethanol, methyl acetate,methyl ethyl ketone (or MEK), methyl formate, methyl n-butyrate, methyln-propyl ketone, methyl t-butyl ether, methylene chloride, methylene,methylhexane, methylpentane, mineral oil, m-xylene, n-butanol, n-decane,n-hexane, nitrobenzene, nitroethane, nitromethane, nitropropane,2-N-methyl-2-pyrrolidinone, n-propanol, octafluoro-1-pentanol, octane,pentane, pentanone, petroleum ether, phenol, propanol, propionaldehyde,propionic acid, propionitrile, propyl acetate, propyl ether, propylformate, propylamine, p-xylene, pyridine, pyrrolidine, t-butanol,t-butyl alcohol, t-butyl methyl ether, tetrachloroethane,tetrafluoropropanol, tetrahydrofuran, tetrahydronaphthalene, toluene,triethyl amine, trifluoroacetic acid, trifluoroethanol,trifluoropropanol, trimethylbutane, trimethylhexane, trimethylpentane,valeronitrile, xylene, xylenol, or any combination thereof.

Suitable inorganic solvents include, for example, water, ammonia, sodiumhydroxide, sulfur dioxide, sulfuryl chloride, sulfuryl chloridefluoride, phosphoryl chloride, phosphorus tribromide, dinitrogentetroxide, antimony trichloride, bromine pentafluoride, hydrogenfluoride, or any combination thereof.

Suitable ionic solutions include, for example, choline chloride, urea,malonic acid, phenol, glycerol, 1-alkyl-3-methylimidazolium,1-alkylpyridinium, N-methyl-N-alkylpyrrolidinium,1-butyl-3-methylimidazolium hexafluorophosphate, ammonium, choline,imidazolium, phosphonium, pyrazolium, pyridinium, pyrrolidnium,sulfonium, 1-ethyl-1-methylpiperidinium methyl carbonate,4-ethyl-4-methylmorpholinium methyl carbonate, or any combinationthereof. Other methylimidazolium solutions can be considered suitable,including 1-ethyl-3-methylimidazolium acetate,1-butyl-3-methylimidazolium tetrafluoroborate,1-n-butyl-3-methylimidazolium tetrafluoroborate,1-butyl-3-methylimidazolium hexafluorophosphate,1-n-butyl-3-methylimidazolium hexafluorophosphate,1-butyl-3-methylimidazolium1,1,1-trifluoro-N-[(trifluoromethyl)sulfonyl]methanesulfonamide,1-butyl-3-methylimidazolium bis(trifluoro methylsulfonyl)imide,1-butyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]amide, and1-butyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide, or anycombination thereof.

Other suitable fluids include halogenated compounds, imides, and amides,such as N-ethyl-N,N-bis(1-methylethyl)-1-heptanaminiumbis[(trifluoromethyl)sulfonyl]imide, ethylheptyl-di-(1-methylethyl)ammonium,1,1,1-trifluoro-N-[(trifluoromethyl)sulfonyl]methane sulfonamide,ethylheptyl-di-(1-methylethyl)ammoniumbis(trifluoromethylsulfonyl)imide,ethylheptyl-di-(1-methylethyl)ammoniumbis[(trifluoromethyl)sulfonyl]amide, or any combination thereof. A fluidcan also include ethylheptyl-di-(1-methylethyl)ammoniumbis[(trifluoromethyl)sulfonyl]imide, N₅N₅N-tributyl-1-octanaminiumtrifluoromethanesulfonate, tributyloctylammonium triflate,tributyloctylammonium trilfuoromethanesulfonate,N,N,N-tributyl-1-hexanaminium bis[(trifluoromethyl)sulfonyl]imide,tributylhexylammonium1,1,1-trifluoro-N-[(trifluoromethyl)sulfonyl]methanesulfonamide,tributylhexylammonium bis(trifluoromethylsulfonyl)imide,tributylhexylammonium bis[trifluoromethyl)sulfonyl]amide,tributylhexylammonium bis[trifluoromethyl)sulfonyl]imide,N,N,N-tributyl-1-heptanaminium bis[trifluoromethyl)sulfonyl]imide,tributylheptylammonium 1,1,1-trifluoro-N-[trifluoromethyl)sulfonyl]methanesulfonamide, tributylheptylammoniumbis(trifluoromethylsulfonyl) imide; tributylheptylammoniumbis[(trifluromethyl)sulfonyl]amide, tributylheptylammoniumbis[(trifluoromethyl)sulfonyl]imide, N,N,N-tributyl-1-octanaminiumbis[(trifluoromethyl) sulfonyl]imide, tributyloctylammonium1,1,1-trifluoro-N-[(trifluoromethyl)sulfonyl]methane sulfonamide,tributyloctylammonium bis(trifluoromethyl)sulfonyl)imide,tributyloctylammonium bis[(trifluoromethyl)sulfonyl]amide,tributyloctylammonium bis[(trifluoromethyl)sulfonyl]imide,1-butyl-3-methylimidazolium trifluoroacetate,1-methyl-1-propylpyrrolidinium1,1,1-trifluoro-N-[(trifluoromethyl)sulfonyl]methanesulfonamide, 1methyl-1-propylpyrrolidinium bis(trifluoro methylsulfonyl)imide,1-methyl-1-propylpyrrolidinium bis[(trifluoromethyl)sulfonyl]amide,1-methyl-1-propylpyrrolidinium bis[(trifluoromethyl)sulfonyl]imide,1-butyl-1-methyl pyrrolidinium1,1,1-trifluoro-N-[(trifluoromethyl)sulfonyl]methanesulfonamide,1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide,1-butyl-1-methylpyrrolidinium bis [(trifluoromethyl)sulfonyl]amide,1-butyl-1-methylpyrrolidinium bis[(trifluoromethyl)sulfonyl]imide,1-butylpyridinium1,1,1-trifluoro-N-[(trifluoromethyl)sulfonyl]methanesulfonamide,1-butylpyridinium bis(trifluoromethylsulfonyl)imide, 1-butylpyridiniumbis[(trifluoromethyl)sulfonyl]amide, 1-butylpyridiniumbis[(trifluoromethyl)sulfonyl]imide, 1-butyl-3-methyl imidazoliumbis(perfluoroethylsulfonyl)imide, butyltrimethylammoniumbis(trifluoromethylsulfonyl)imide, 1-octyl-3-methylimidazolium1,1,1-trifluoro-N-[(trifluoromethyl)sulfonyl]methanesulfonamide,1-octyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide,1-octyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]amide,1-octyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide,1-ethyl-3-methylimidazolium tetrafluoroborate,N₅N₅N-trimethyl-1-hexanaminium bis[(trifluoromethyl)sulfonyl]imide,hexyltrimethylammonium1,1,1-trifluoro-N-[(trifluoromethyl)sulfonyl]methanesulfonamide,hexyltrimethylammonium bis(trifluoromethylsulfonyl)imide,hexyltrimethylammonium bis[(trifluoromethyl)sulfonyl]amide,hexyltrimethylammonium bis[(trifluoromethyl)sulfonyl]imide,N,N,N-trimethyl-1-heptanaminium bis[(trifluoromethyl)sulfonyl]imide,heptyltrimethylammonium1,1,1-trifluoro-N-[(trifluoromethyl)sulfonyl]methanesulfonamide,heptyltrimethylammonium bis(trifluoromethylsulfonyl)imide,heptyltrimethylammonium bis[(trifluoromethyl)sulfonyl]amide,heptyltrimethylammonium bis[(trifluoromethyl)sulfonyl]imide,N,N,N-trimethyl-1-octanaminium bis[(trifluoromethyl)sulfonyl]imide,trimethyloctylammonium1,1,1-trifluoro-N-[(trifluoromethyl)sulfonyl]methanesulfonamide,trimethyloctylammonium bis(trifluoromethylsulfonyl)imide,trimethyloctylammonium bis[(trifluoromethyl)sulfonyl]amide,trimethyloctylammonium bis[trifluoromethyl)sulfonyl]imide,1-ethyl-3-methylimidazolium ethyl sulfate, or any combination thereof.

Control over surface-embedding of additives can be achieved through theproper balancing of the swelling-dispersion-evaporation-applicationstages. This balance can be controlled by, for example, a solvent-hostmaterial interaction parameter, sizes of additives, reactivity andvolatility of an embedding fluid, impinging additive momentum orvelocity, temperature, humidity, pressure, and others factors. Moreparticularly, relevant processing parameters for surface-embedding arelisted below for some embodiments of the invention:

Embedding Fluid Selection:

-   -   Compatibility of embedding fluid with surface (e.g., matching or        comparison of Hildebrand and Hansen solubility parameters,        dielectric constant, partition coefficient, pKa, etc.)    -   Evaporation rate, boiling point, vapor pressure, enthalpy of        vaporization of embedding fluid    -   Diffusion of embedding fluid into surface: thermodynamic and        kinetics considerations    -   Viscosity of embedding fluid    -   Surface tension of embedding fluid, wicking, and capillary        effects    -   Azeotroping, miscibility, and other interactions with other        fluids

Application Conditions:

-   -   Duration of fluid-surface exposure    -   Temperature    -   Humidity    -   Application method (e.g., spraying, printing, rolling coating,        gravure coating, slot-die, cup coating, blade coating,        airbrushing, immersion, dip coating, etc.)    -   Impact/momentum/velocity of additives onto surface (e.g., may        influence depth or extent of embedding)    -   Shear applied to solvent between host material and applicator    -   Post-processing conditions (e.g., heating, evaporation, fluid        removal, air-drying, etc.)

Host Material:

-   -   Surface energy    -   Roughness and surface area    -   Pre-treatments (e.g., ultraviolet ozonation, base etch,        cleaning, solvent priming, heating, curing, vacuum, etc.)    -   Dispersion/suspension of additives in fluid prior to embedding        (e.g., additives can remain dispersed in solution through        physical agitation, chemical/capping stabilization, steric        stabilization, or are inherently solubilized)    -   Mitigation of undesired effects (e.g., hazing, crazing,        blushing, irreversible destruction of host material, uneven        wetting, roughness, etc.)

Some, or all, of the aforementioned parameters can be altered orselected to tune a depth of embedding of additives into a given hostmaterial. For example, higher degrees of embedding deep into a surfaceof a host material can be achieved by increasing a solvency power of anembedding fluid interacting with the host material, matching closelyHansen solubility parameters of the embedding fluid-substrate,prolonging the exposure duration of the embedding fluid in contact withthe host material, increasing an amount of the embedding fluid incontact with the host material, elevating a temperature of the system,increasing a momentum of additives impinging onto the host material,increasing a diffusion of either, or both, of the embedding fluid andthe additives into the host material or any combination thereof.

The following Table 2 provides examples of some embedding fluidssuitable for embedding additives into dry compositions composed ofparticular polymers, according to an embodiment of the invention. Usingthe processing parameters set forth above, it will be understood thatother embedding fluids can be selected for these particular polymers, aswell as other types of polymers, ceramics, and ceramic precursors.

TABLE 7 Polymer Embedding Fluids Acrylonitrile acetone, dichloromethane,dichloromethane/mineral spirits 80/20 butadiene styrene vol %, methylacetate, methylethylketone, tetrahydrofuran for THF), (or ABS) ethyllactate, cyclohexanone, toluene, tetrafluoropropanol (or TFP),trifluoroethanol (or TFE), hexafluorolsopropanol (or HFIP), or anycombination thereof Polycarbonate cyclohexanone, dichloromethane, 60 vol% methyl acetate/20 vol % ethyl acetate/20 vol % cyclohexanone,tetrahydrofuran, toluene, tetrafluoropropanol, trifluoroethanol,hexafluoroisopropanol, methylethylketone, acetone, other pure ketones,or any combination thereof Acrylic- dichloromethane, methylethylketone,tetrafluoropropanol, polyacrylate, trifluoroethanol,hexafluoroisopropanol, terpineol, 1-butanol, polymethyl isopropanol,tetrahydrofuran, terpineol, trifluoroethanol/isopropanol, methacrylateother fluorinated alcohols, or any combination thereof for PMMA)Polystyrene acetone, dichloromethane, tetrahydrofuran, toluene, 50 vol %acetone/ 50 vol % tetrahydrofuran, or any combination thereof Polyvinylchloride tetrahydrofuran, 50% acetone/50% tetrahydrofuran, or any forPVC) combination thereof Ethylene tetrahydrofuran, dichloromethane,alcohol, or any combination thereof vinyl acetate for EVA)

Fluids (e.g., embedding fluids and carrier fluids) can also includesalts, surfactants, stabilizers, and other agents useful in conferring aparticular set of characteristics on the fluids. Stabilizers can beincluded based on their ability to at least partially inhibitinter-additive agglomeration. Other stabilizers can be chosen based ontheir ability to preserve the functionality of additives. BHT, forinstance, can act as a good stabilizer and as an antioxidant. Otheragents can be used to adjust rheological properties, evaporation rate,and other characteristics.

Fluids and additives can be applied so as to be largely stationaryrelative to a surface of a dry composition. In other embodiments,application is carried out with relative movement, such as by spraying afluid onto a surface, by conveying a dry composition through a fallingcurtain of a fluid, or by conveying a dry composition through a pool orbath of a fluid. Application of fluids and additives can be effected byairbrushing, atomizing, nebulizing, spraying, electrostatic spraying,pouring, rolling, curtaining, wiping, spin casting, dripping, dipping,painting, flowing, brushing, immersing, patterning (e.g., stamping,inkjet printing, controlled spraying, controlled ultrasonic spraying,and so forth), flow coating methods (e.g., slot die, capillary coating,meyer rod, cup coating, draw down, and the like), printing, gravureprinting, lithography, offset printing, roll coating, inkjet printing,intaglio printing, or any combination thereof. In some embodiments,additives are propelled, such as by a sprayer, onto a surface, therebyfacilitating embedding by impact with the surface. In other embodiments,a gradient is applied to a fluid, additives, or both. Suitable gradientsinclude magnetic and electric fields. The gradient can be used to apply,disperse, or propel the fluid, additives, or both, onto a surface. Insome embodiments, the gradient is used to manipulate additives so as tocontrol the extent of embedding. An applied gradient can be constant orvariable. Gradients can be applied before a dry composition is softenedor swelled, while the dry composition remains softened or swelled, orafter the dry composition is softened or swelled. It is contemplatedthat a dry composition can be heated to achieve softening, and thateither, or both, a fluid and additives can be heated to promoteembedding.

Application of fluids and additives and embedding of the additives canbe spatially controlled to yield patterns. In some embodiments, spatialcontrol can be achieved with a physical mask, which can be placedbetween an applicator and a surface to block a segment of appliedadditives from contacting the surface, resulting in controlledpatterning of additive embedding. In other embodiments, spatial controlcan be achieved with a photomask. A positive or negative photomask canbe placed between a light source and a surface, which can correspond toa photoresist. Light transmitted through non-opaque parts of thephotomask can selectively affect a solubility of exposed parts of thephotoresist, and resulting spatially controlled soluble regions of thephotoresist can permit controlled embedding of additives. In otherembodiments, spatial control can be achieved through the use of electricgradients, magnetic gradients, electromagnetic fields, thermalgradients, pressure or mechanical gradients, surface energy gradients(e.g., liquid-solid-gas interfaces, adhesion-cohesion forces, andcapillary effects), or any combination thereof. Application of anoverlying coating (e.g., as illustrated in FIG. 2C and FIG. 2G) can becarried out in a similar fashion. For example, in the case of ITO oranother transparent metal oxide, a coating can be sputtered onto acomposition with surface-exposed, surface-embedded additives. In thecase of an electrically conductive polymer, a carbon-based coating, andother types of coatings, an electrically conductive material can beapplied by coating, spraying, flow coating, and so forth. Spatialcontrol can also be achieved by printing a material that differs from ahost material and in which embedding does not occur (or is otherwiseinhibited).

As noted above, additives can be dispersed in an embedding fluid, andapplied to a dry composition along with the embedding fluid via one-stepembedding. Additives also can be applied to a dry composition separatelyfrom an embedding fluid via two-step embedding. In the latter scenario,the additives can be applied in a wet form, such as by dispersing in acarrier fluid or by dispersing in the same embedding fluid or adifferent embedding fluid. Still in the latter scenario, the additivescan be applied in a dry form, such as in the form of aerosolized powder.It is also contemplated that the additives can be applied in a quasi-dryform, such as by dispersing the additives in a carrier fluid that isvolatile, such as methanol, another low boiling point alcohol, oranother low boiling point organic solvent, which substantially vaporizesprior to impact with a dry composition.

By way of example, one embodiment involves spraying, airbrushing, orotherwise atomizing a solution of nanowires or other additives dispersedin an appropriate carrier fluid onto a dry composition.

As another example, one embodiment involves pre-treating a drycomposition by spraying or otherwise contacting an embedding fluid withthe dry composition, and then, after the passage of time t₁, spraying orairbrushing nanowires or other additives with velocity such that thecombination of the temporarily softened dry composition and the velocityof the impinging nanowires allow rapid and durable surface-embedding ofthe nanowires, t₁ can be, for example, in the range of about 0nanosecond to about 24 hours, such as from about 1 nanosecond to about24 hours, from about 1 nanosecond to about 1 hour or from about 1 secondto about 1 hour. Two spray nozzles can be simultaneously or sequentiallyactivated, with one nozzle dispensing the embedding fluid, and the othernozzle dispensing, with velocity, atomized nanowires dispersed in acarrier fluid towards the dry composition. Air-curing or highertemperature annealing optionally can be included.

As another example, one embodiment involves spraying, airbrushing, orotherwise atomizing a solution of nanowires or other additives dispersedin a carrier fluid onto a dry composition. After the passage of time t₂,a second spraying, airbrushing, or atomizing operation is used to applyan embedding fluid so as to permit efficient surface-embedding of thenanowires. t₂ can be, for example, in the range of about 0 nanosecond toabout 24 hours, such as from about 1 nanosecond to about 24 hours, fromabout 1 nanosecond to about 1 hour or from about 1 second to about 1hour. Two spray nozzles can be simultaneously or sequentially activated,with one nozzle dispensing the embedding fluid, and the other nozzledispensing, with velocity, atomized nanowires dispersed in the carrierfluid towards the dry composition. Air-curing or higher temperatureannealing optionally can be included.

As a further example, one embodiment involves applying nanowires orother additives onto a dry composition composed of sodium silicate oranother alkali metal silicate or other solid glass. Eithersimultaneously or as a separate operation, an embedding fluid composedof heated, basic water is applied in liquid or vapor form to the sodiumsilicate at either room temperature or elevated temperature, whichcauses the sodium silicate to at least partially dissolve, therebypermitting entry of the nanowires into the dissolved sodium silicate.The water is evaporated or otherwise removed, causing the sodiumsilicate to re-solidify with the nanowires embedded within the sodiumsilicate. Air-curing or higher temperature annealing optionally can beincluded.

Attention next turns to FIG. 5C, which illustrates a manufacturingmethod for surface embedding additives 522 into a wet composition 518,according to an embodiment of the invention. Referring to FIG. 5C, thewet composition 518 is applied to a substrate 520 in the form of acoating that is disposed on top of the substrate 520. The wetcomposition 518 can correspond to a dissolved form of a host materialand, in particular, can include a dissolved form of any materialpreviously listed as suitable host materials, such as a polymer, aceramic, a ceramic precursor, or any combination thereof. It is alsocontemplated that the wet composition 518 can correspond to a hostmaterial precursor, which can be converted into the host material bysuitable processing, such as drying, curing, cross-linking,polymerizing, or any combination thereof. For example, the wet coatingcomposition 518 can be a coating that is not fully cured or set, across-linkable coating that is not fully cross-linked, which can besubsequently cured or cross-linked using suitable polymerizationinitiators or cross-linking agents, or a coating of monomers, oligomers,or a combination of monomers and oligomers, which can be subsequentlypolymerized using suitable polymerization initiators or cross-linkingagents. In some embodiments, the wet composition 518 can include amaterial with a liquid phase as well as a solid phase, or can include amaterial that is at least partially liquid or has properties resemblingthose of a liquid, such as a semisolid, a gel, and the like. Thesubstrate 520 can be transparent or opaque, can be flexible or rigid,and can be composed of, for example, a polymer, an ionomer, EVA, PVB,TPO, TPU, PE, PET, PETG, polycarbonate, PVC, PP, acrylic-based polymer,ABS, siloxane, silane, sol-gel, ceramic, or any combination thereof, aswell as any other material previously listed as suitable host materials.The substrate 520 can serve as a temporary substrate that issubsequently removed during device assembly, or can be retained in aresulting device as a layer or other component of the device.

Next, according to the option on the left-side of FIG. 5C, the additives522 are applied to the wet composition 518 prior to drying or while itremains in a state that permits embedding of the additives 522 withinthe wet composition 518. In some embodiments, application of theadditives 522 is via a flow coating method (e.g., slot die, capillarycoating, meyer rod, cup coating, draw down, and the like). Although notillustrated on the left-side, it is contemplated that an embedding fluidcan be simultaneously or separately applied, to the wet composition 518to facilitate the embedding of the additives 522. Subsequently, theresulting host material 524 has at least some of the additives 522partially or fully embedded into a surface of the host material 524.Suitable processing can be carried out to convert the wet composition518 into the host material 524. During device assembly, the hostmaterial 524 with the embedded additives 522 can be laminated orotherwise connected to adjacent device layers, or can serve as asubstrate onto which adjacent device layers are formed, laminated, orotherwise applied.

Certain aspects regarding the application of the additives 522 and theembedding of the additives 522 in FIG. 5C can be carried out usingsimilar processing conditions and materials as described above for FIG.5A and FIG. 5B, and those aspects need not be repeated below. Thefollowing provides additional details on embodiments related to ceramicsand ceramic precursors.

In some embodiments, additives are embedded into a wet composition inthe form of a coating of a liquid ceramic precursor, which may include asolvent and a set of reactive species. The embedding is carried outbefore the solvent has fully dried and/or after drying but beforecuring, followed by the option of curing or otherwise converting theceramic precursor to a fully condensed or restructured glass. Examplesof ceramic precursor reactive species include spin-on glasses, silanes(e.g., Si(OR)(OR′)(OR″)(R′″), Si(OR)(OR′)(R″)(R′″), andSi(OR)(R′)(R″)(R′″), where R, R′, R″, and R′″ are independently selectedfrom alkyl groups, alkenyl groups, alkynyl groups, and aryl groups),titanium analogues of silanes, cerium analogues of silanes, magnesiumanalogues of silanes, germanium analogues of silanes, indium analoguesof silanes, tin analogues of silanes, zinc analogues of silanes,aluminium analogues of silanes, any mixed metal analogues of silanes,siloxanes (e.g., Si(OR)(OR′)(OR″)(OR′″), where R, R′, R″, and R′″ areindependently selected from alkyl groups, alkenyl groups, alkynylgroups, and aryl groups), titanium analogues of siloxanes, ceriumanalogues of siloxanes, magnesium analogues of siloxanes, germaniumanalogues of siloxanes, indium analogues of siloxanes, tin analogues ofsiloxanes, zinc analogues of siloxanes, aluminium analogues ofsiloxanes, any mixed metal analogues of siloxanes, alkali metalsilicates (e.g., sodium silicate and potassium silicate), or anycombination thereof. As more specific examples, a ceramic precursorreactive species can be a siloxane such as tetramethoxysilane (or TMOS),tetraethoxysilane (or TEOS), tetra(isopropoxy)silane, titanium analoguesthereof, cerium analogues thereof, magnesium analogues thereof,germanium analogues thereof, indium analogues thereof, tin analoguesthereof, zinc analogues thereof, aluminium analogues thereof, any mixedmetal analogues thereof, or any combination thereof.

In some embodiments, reactive species are at least partially reacted,prior to embedding of additives. Reaction can be carried out by, forexample, hydrolysis in the presence of an acid and a catalyst andfollowed by condensation, thereby yielding oligomeric or polymericchains. For example, slimes and siloxanes can undergo partialcondensation to yield oligomeric or polymeric chains with Si—O—Silinkages, and at least some side groups corresponding to (OR) or (R).

In some embodiments, a liquid ceramic precursor includes at least twodifferent types of reactive species. The different types of species canreact with each other, as exemplified, by two or more of TEOS, TMOS,and, tetra(isopropoxy)silane, and can be suitably selected in order tocontrol evaporation rate and pre-cured film morphology. Reactive specieswith larger side groups, such as isopropoxy in the case oftetra(isopropoxy)silane versus methoxy in the case of TMOS, can yieldlarger pore sizes when converted into a gel, which larger pore sizes canfacilitate swelling in the presence of an embedding fluid. Also, uponhydrolysis, larger side groups can be converted into correspondingalcohols with lower volatility, such as isopropyl alcohol in the case oftetra(isopropoxy)silane versus methanol in the case of TMOS, which canslow the rate of drying. In other embodiments, the different types ofspecies are not likely to react, such as sodium silicate andtetra(isopropoxy)silane. This can afford facile curing properties of abulk of a matrix formed by drying the silicate, while retaining someamount of delayed condensation to allow embedding of additives.

In some embodiments, reactive species, either prior to reaction orsubsequent to reaction, can include some amount of Si—C or Si—C—Silinkages, which can impart toughness, porosity, or other desirablecharacteristics, such as to allow trapping of a solvent to slow the rateof drying or to promote swelling in the presence of an embedding fluid.

In some embodiments, reactive species, either prior to reaction orsubsequent to reaction, can include Si—OR groups, where R is a longchain side group with low volatility to slow the rate of drying of acoating of a liquid ceramic precursor. In other embodiments, reactivespecies can include Si—R′ groups, where R′ is a long chain side groupwith low volatility to slow the rate of drying of a coating of a liquidceramic precursor. Either, or both, of R and R′ also can havecharacteristics to interact and retain a solvent, thereby slowing thedrying process. For example, R and R′ can have polarity, non-polarity,aliphatic characteristics, or other characteristics that match those ofthe solvent.

In some embodiments, a solvent included in a liquid ceramic precursorcan include water, an alcohol, dimethylformamide, dimethyl sulfoxide,another polar solvent, another non-polar solvent, any other suitablefluid listed above, or any combination thereof. For example, the solventcan be non-polar, and water can be used heterogeneously duringhydrolysis, with complete condensation occurring after drying a coatingof the ceramic precursor. As another example, a combination of solventscan be selected, such that a major component has high volatility inorder to carry, wet, or level reactive species, whereas a minorcomponent has low volatility to delay drying of the coating. It is alsocontemplated that the reactive species can form a relatively smallfraction of a total coating volume to slow drying.

In some embodiments, a liquid ceramic precursor can be applied to asubstrate using a wide variety of coating methods, such as aroll-to-roll process, roll coating, gravure coating, slot dye coating,knife coating, spray coating, and spin coating. For example, the liquidceramic precursor can be applied by spin coating, and additives can bedeposited upon the start of spin coating or after the start of spincoating, but before the resulting coating has dried on a spinner.

In some embodiments, additives can be dispersed in a carrier fluid, andthen applied in a wet form to a liquid ceramic precursor. The carrierfluid can include the same solvent (or another solvent having similarcharacteristics) as a low volatility component of the liquid ceramicprecursor in order to reduce or avoid adverse interaction upon impact.It is also contemplated that the carrier fluid can be volatile (e.g.methanol or another low boiling alcohol), which substantially vaporizesprior to impact. Another example of a suitable carrier fluid is water.

In some embodiments, curing can be carried out after embedding such thata liquid, ceramic precursor is converted into a glass. For example,curing can involve heatina to a temperature in the range of about 400°C. to about 500° C. in nitrogen (optionally containing water vapor(possibly saturated)), heating up to a temperature sufficient to removeresidual solvent (e.g., from about 100° C. to about 150° C.), or heatingto a temperature in the range of about 800° C. to about 900° C. to forma fully condensed glass. Curing can be omitted, such as in the case ofsodium silicate (or another alkali silicate) that can dry under ambientconditions into a robust “clear coat.” In some embodiments, curing canalso serve as a sintering/annealing operation for embedded nanowires orother additives. In some embodiments, pre-curing can be carried outbefore embedding in order to stabilize a coating to withstand shear orfluid forces, but still be in astute to allow embedding of additives.

Turning back to FIG. 5C and, referring to the option on the right-side,the wet composition 518 is initially converted into a dry composition526 by suitable processing, such as by at least partially drying,curing, cross-linking, polymerization, or any combination thereof. Next,the additives 522 and an embedding fluid 528 are applied to the drycomposition 526. The additives 522 can be in solution or otherwisedispersed in the embedding fluid 528, and can be simultaneously appliedto the dry composition 526 via one-step embedding. Alternatively, theadditives 522 can be separately applied to the dry composition 526before, during, or after the embedding fluid 528 treats the drycomposition 526. As noted above, the separate application of theadditives 522 can be referred as two-step embedding. Subsequently, theresulting host material 524 has at least some of the additives 522partially or fully embedded into the surface of the host material 524.Optionally, suitable processing can be carried out to convert the drycomposition 526 into the host material 524, such as by additionaldrying, curing, cross-linking, polymerization, or any combinationthereof. Any, or all, of the manufacturing stages illustrated in FIG. 5Ccan be carried out in the presence of a vapor environment of a suitablefluid (e.g., an embedding fluid or other suitable fluid) to facilitatethe embedding of the additives 522, to slow drying of the wetcomposition 518, or both.

Certain aspects regarding the application of the additives 522 and theembedding fluid 528 and the embedding of the additives 522 in FIG. 5Ccan be carried out using similar processing conditions and materials asdescribed above for FIG. 5A and FIG. 5B, and those aspects need not berepeated below. In particular, and in at least certain aspects, theprocessing conditions for embedding the additives 522 into the drycomposition 526 of FIG. 5C can be viewed as largely parallel to thoseused when embedding the additives 512 into the dry composition 508 ofFIG. 5B. The following provides further details on embodiments relatedto ceramics and ceramic precursors.

In some embodiments, additives are embedded into a dry composition inthe form of a coating of an uncured (or not fully cured) ceramicprecursor, which has been initially dried but is later swelled by anembedding fluid. This is followed by drying of the embedding fluid,contracting a coating matrix around the additives. In some instances,the embedding fluid can include the same solvent (or another solventhaving characteristics) as that of the ceramic precursor prior todrying, in which case the processing conditions can be viewed as largelyparallel to those used when embedding additives into a wet composition.Embedding of additives is followed by the option of curing or otherwiseconverting the ceramic precursor to a fully condensed or restructuredglass.

In some embodiments, reactive species are selected to be initiallyoligomeric or polymeric (e.g., as opposed to monomers like TEOS or TMOS)prior to hydrolysis and condensation. Such oligomeric or polymeric formof the reactive species can promote swelling in the presence of anembedding fluid. Examples include reactive species available under thedesignations of Methyl 51, Ethyl 50, Ethyl 40, and the like. In otherembodiments, oligomeric or polymeric reactive species can be formed byreacting monomeric reactive species, such as via hydrolysis andcondensation, to reach a desired molecular weight. The oligomeric orpolymeric reactive species can be combined with monomeric reactivespecies, with the different species being miscible, partially miscible,or largely immiscible. Such oligomeric or polymeric reactive speciesalso can be used according to the left-side option of FIG. 5C, namely byincluding such oligomeric or polymeric reactive species in a coating ofa liquid ceramic precursor and embedding additives into the coatingprior to drying, optionally in the presence of an embedding fluid.

In some embodiments, reactive species can include monomers with up totwo reactive sites, such as silicones, silsesquioxanes, and the like.Upon reaction, such reactive species can form polymer chains with acontrollable amount of cross-linking, thereby promoting swelling in thepresence of an embedding fluid and facilitating embedding of additives.For example, the reactive species can include Si(OR)₂R′₂, such asSi(OCH₂CH₃)₂(CH₃)₂, which typically does not crosslink below about 400°C., can swell with an embedding fluid due to its polymeric nature, andcan be subsequently cross-linked into a glass by heating to above 400°C. Such polymeric reactive species also can be used according to theleft-side option of FIG. 5C, namely by including such polymeric reactivespecies in a coating of a liquid ceramic precursor and embeddingadditives into the coating prior to drying, optionally in the presenceof an embedding fluid.

EXAMPLES

The following examples describe specific aspects of some embodiments ofthe invention to illustrate and provide a description for those ofordinary skill in the art. The examples should not be construed aslimiting the invention, as the examples merely provide specificmethodology useful in understanding and practicing some embodiments ofthe invention.

Example 1 Formation of Surface-Embedded Encapsulant Layer

This example sets forth the formation of a surface-embedded encapsulantlayer with spectral shifting functionality that can be laminatedadjacent to a front surface of a solar device. A sheet of ethylene vinylacetate (or EVA) is sprayed with a solution of a solvent system and aphosphor. Another encapsulant material, such as polyvinyl alcohol (orPVA), polyvinyl butaryl (or PVB), or thermoplastic polyurethane (orTPU), can be used in place of, or in combination with, EVA. The EVAsheet can be between about 250 μm and about 2.5 mm in thickness, such asabout 500 μm in thickness. By way of example, the solvent system can betetrahydrofuran and dichloromethane in a combination, and the phosphorcan be a down-shifting species such as either, or both, oftris(dibenzoylmethane)(phenanthroline)europium(III) (or Eu(dbm)₃phen)and tris[3-(trifluoromethylhydroxymethilene)-d-camphorate]europium(III)(or Eu(tfc)₃). Another solvent or solvent combination can be used, andanother phosphor or other type of additive can be used in place of, orin combination with, the phosphor. The phosphor is mixed into thesolvent system prior to spray application. The solution sprayed onto theEVA sheet temporarily softens or solubilizes a top surface of the EVAsheet by a depth of about 500 nm, and this softening (in combinationwith a velocity of the impinging phosphor) permits rapid surfaceembedding of the phosphor into the EVA sheet. Spray conditions caninvolve about 1 ml to about 16 ml of the solution onto each square footof the EVA sheet at a spray nozzle distance of about 6 inches from theEVA sheet, and an atomizing pressure of about 20 pounds per square inch.In such manner, the phosphor is localized within an embedding region andsecurely embedded beneath the top surface of the EVA sheet by a depth ofabout 500 nm. Following spray-embedding of the phosphor evaporation ofthe solvent system proceeds in a rapid manner, rendering the EVA sheetdry within about 5 seconds. Curing or other suitable processing canproceed next with the phosphor now securely embedded into the topsurface of the EVA sheet. The spray-embedding process can be conductedin a substantially continuous, roll-to-roll fashion, where the EVA sheetis wound and unwound substantially continuously.

Example 2 Formation of Surface-Embedded Encapsulant Layer

This example sets forth the formation of a surface-embedded encapsulantlayer that can be incorporated, within a solar device. Additives, suchas in the form of silver nanowires suspended in an alcohol, are sprayedonto a surface of an EVA sheet. After the alcohol has evaporated leavinga superficially deposited layer of the silver nanowires on top of theEVA sheet, tetrahydrofuran is sprayed onto the surface of the EVA sheet,softening and embedding the nanowires into the EVA sheet. The amount oftetrahydrofuran can be controlled to tune the degree of embedding of thenanowires partially or fully beneath the surface of the EVA sheet. Theresulting nanowire-embedded EVA sheet can exhibit light scatteringcharacteristics and electrical conductivity due to percolation ofcontacting nanowires adjacent to the surface of the EVA sheet. Thisembedding process can be carried out at room temperature and atmosphericpressure. The nanowire-embedded EVA sheet can be laminated onto either,or both, a glass cover and a photoactive layer via vacuum laminationduring device assembly. The resulting encapsulated solar device has anelectrically conducting encapsulant layer to collect or augment thecollection of current adjacent to a front electrode, as well as toenhance light scattering towards or otherwise induce absorption ofsunlight by the photoactive layer, such as for sunlight at obliqueangles of incidence. Additionally, the encapsulant layer offers enhancedthermal conductivity to distribute heat more efficiently and evenlyacross the solar device to ensure more reliable performance. Other typesof additives can be used in place of, or in combination with, silvernanowires.

Example 3 Formation of Surface-Embedded Encapsulant Layer

About 250 mg of Eu(dbm)₃phen was combined with about 13 mL oftetrahydrofuran. The entirety of this solution was sprayed using aniwata Eclipse HP-CS air brush onto 19 cm×27 cm pieces of Mars Rock EVAsheet providing a coverage of about 0.487 mg/cm². The EVA sheet was cutinto 2.1 inches×2.1 inches pieces. 2 inches×2 inches pieces of borofloatglass from McMaster were cleaned with Micro 90 detergent and rinsed withdionized water and isopropanol, followed, by about 30 minutes ofUV-ozone treatment. The glass pieces were laminated to crystallinesilicon photovoltaic cells obtained from Mars Rock. One piece waslaminated with untreated EVA. The other piece was laminated with EVAtreated with the europium phosphor. Lamination was carried out bysandwiching each EVA piece between a glass piece and a photovoltaiccell, followed by application of vacuum started empty at about 99° C.The assembly was placed into an oven, causing the temperature to drop toabout 74° C. The oven was evacuated to −25 mm Hg, during which time thetemperature moved up to about 86° C. The assembly was left in the ovenfor about 20 minutes under vacuum.

Example 4 Characterization of Surface-Embedded Structures

FIG. 11 illustrates various configurations of additive concentrationsrelative to an embedding surface of a host material, where non-zeroadditive concentrations denote the embedding regions. For all of theplots in FIG. 11, the host material is confined between the x-axisvalues of 0 and 10. If a coating is present, then it is deposited on topof the host material, and is located between x=−2 and x=0. The x-axisdenote the depth/thickness of the host material from the embeddingsurface. The first plot is of a substrate that has been bulkincorporated or compounded with additives mixed throughout the bulk ofthe entire substrate. Its additive concentration is depicted as auniform distribution held at y=0.2 concentration. The second plotillustrates a similar geometry, but with additives mixed throughout acoating material.

Surface-embedded additives can be localized in a discrete step or deltafunction as a function of thickness or depth from the embedding surfaceof the host material, as illustrated in FIG. 11A. Alternatively, theadditives can be largely localized at the embedding surface but having aconcentration tailing off the deeper into the embedding surface as inFIG. 11B or the closer to the embedding surface as in FIG. 11E.Additives can be surface-embedded fully beneath the embedding surface inthe fashion of FIG. 11C, where there is a maximum concentration ofadditives at a discrete depth followed by a tailing off of additiveconcentration from that discrete depth below the embedding surface inboth directions. Multiple depths of additive embedding can be achievedby adjusting parameters to tune the depth of embedding, and multipleoperations can be performed onto the substrate to permit this multiplelayered embedding geometry as captured in FIG. 11D and FIG. 11F. Similargeometries can be achieved by surface-embedding via the aforementionedapproaches but on (or in) a substrate that has already been bulkincorporated, as in FIG. 11G through FIG. 11I. Similar geometries can beachieved by surface-embedding not only into a substrate material butalso into a coating material, as those illustrated in FIG. 11J throughFIG. 11L.

While the invention has been described with reference to the specificembodiments thereof, it should be understood by those skilled in the artthat various changes may be made and equivalents may be substitutedwithout departing from the true spirit and scope of the invention asdefined by the appended claims. In addition, many modifications may bemade to adapt a particular situation, material, composition of matter,method, or process to the objective, spirit and scope of the invention.All such modifications are intended to be within the scope of the claimsappended hereto, in particular, while the methods disclosed herein havebeen described with reference to particular operations performed in aparticular order, it will be understood that these operations may becombined, sub-divided, or re-ordered to form an equivalent methodwithout departing from the teachings of the invention. Accordingly,unless specifically indicated herein, the order and grouping of theoperations are not limitations of the invention.

1. A solar device comprising: a front cover; a back cover; a photoactivelayer disposed between the front cover and the back cover; and anencapsulant layer disposed between the front cover and the back coverand adjacent to the photoactive layer, wherein the encapsulant layerincludes additives at least partially embedded into the encapsulantlayer, the additives are at least one of electrically conductive andsemiconducting, and the additives include at least one of asub-nano-sized additive, a nano-sized additive, and a micron-sizedadditive.
 2. The solar device of claim 1, wherein the encapsulant layerhas an embedding surface, and the additives are localized within anembedding region adjacent to the embedding surface.
 3. The solar deviceof claim 2, wherein the embedding surface is facing the photoactivelayer.
 4. The solar device of claim 2, wherein a thickness of theembedding region is less than an overall thickness of the encapsulantlayer.
 5. The solar device of claim 4, wherein the thickness of theembedding region is no greater than 50% of the overall thickness of theencapsulant layer.
 6. The solar device of claim 5, wherein the thicknessof the embedding region is no greater than 20% of the overall thicknessof the encapsulant layer.
 7. The solar device of claim 1, furthercomprising a set of bus bars at least partially covered by theencapsulant layer and extending into the encapsulant layer.
 8. The solardevice of claim 1, wherein a loading of the additives in the encapsulantlayer is above an electrical percolation threshold.
 9. The solar deviceof claim 1, wherein the encapsulant layer has a sheet resistance that isno greater than 100 Ω/sq.
 10. The solar device of claim 9, wherein thesheet resistance is no greater than 15 Ω/sq.
 11. The solar device ofclaim 1, wherein the encapsulant layer is disposed between the frontcover and the photoactive layer, and the encapsulant layer has asolar-flux weighted transmittance of at least 85%.
 12. The solar deviceof claim 1, wherein the additives are in electrical contact with thephotoactive layer, and function as an electrode of the solar device. 13.A solar device comprising: a set of front device layers; a set of backdevice layers; and a photoactive layer disposed between the set of frontdevice layers and the set of back device layers, wherein at least one ofthe set of front device layers and the set of back device layersincludes: a host material having an embedding surface; and additives atleast partially embedded into the host material and localized within anembedding region adjacent to the embedding surface, wherein a thicknessof the embedding region is less than an overall thickness of the hostmaterial.
 14. The solar device of claim 13, wherein the thickness of theembedding region is no greater than 5 times a characteristic dimensionof the additives.
 15. The solar device of claim 14, wherein thethickness of the embedding region is no greater than 2 times thecharacteristic dimension.
 16. The solar device of claim 14, wherein atleast one of the additives is embedded into the host material to anextent of not more than 100% of the characteristic dimension.
 17. Thesolar device of claim 14, wherein at least one of the additives isembedded into the host material to an extent of more than 100% of thecharacteristic dimension, but localized adjacent to the embeddingsurface.
 18. The solar device of claim 13, wherein the additives includeat east one of a nanotube, a nanowire, and a nanoparticle.
 19. The solardevice of claim 13, wherein the additives include a phosphor.
 20. Thesolar device of claim 19, wherein the phosphor is configured to performspectral shifting of incident light to match an absorption of thephotoactive layer.
 21. The solar device of claim 19, wherein thephosphor is configured to absorb light in the ultraviolet range and emitlight in at least one of the visible range and the infrared range. 22.The solar device of claim 19, wherein the phosphor is configured toabsorb light in the infrared range and emit light in the visible range.23. The solar device of claim 19, wherein the phosphor is configured toabsorb light in at least one of the ultraviolet range and the visiblerange and emit light in at least one of the visible range and theinfrared range.
 24. The solar device of claim 13, wherein the at leastone of the set of front device layers and the set of back device layerscorresponds to one of a front cover and a back cover.
 25. The solardevice of claim 13, wherein the at least one of the set of front devicelayers and the set of back device layers corresponds to an encapsulantlayer.
 26. A solar device comprising: a photovoltaic cell; and aluminescent solar concentrator optically connected to the photovoltaiccell, wherein the luminescent solar concentrator includes: a frontcover; a back cover; and an interlayer disposed between the front coverand the back cover, wherein the interlayer includes a phosphor at leastpartially embedded into the interlayer and localized within an embeddingregion of the interlayer, such that a remainder of the interlayer issubstantially devoid of the phosphor, and wherein the phosphor isconfigured to absorb incident solar radiation and emit radiation that isguided towards the photovoltaic cell.
 27. The solar device of claim 26,wherein the front cover is configured to face the incident solarradiation, and the phosphor is localized within the embedding regionthat is adjacent to the front cover.
 28. The solar device of claim 27,wherein the phosphor is fully embedded into the interlayer, butlocalized adjacent to the front cover.
 29. The solar device of claim 26,wherein the interlayer further includes a host material including atleast one of a polymer and a ceramic, and the phosphor is at leastpartially embedded into the host material.
 30. The solar device of claim26, wherein the phosphor is configured to perform spectral shifting ofthe incident solar radiation.
 31. The solar device of claim 26, whereina thickness of the embedding region is no greater than 40% of an overallthickness of the interlayer.
 32. The solar device of claim 31, whereinthe thickness of the embedding region is no greater than 30% of theoverall thickness of the interlayer.
 33. A device with surface-embeddedadditives, comprising; a first cover; a second cover; and an interlayerdisposed between the first cover and the second cover, wherein theinterlayer includes: a host material; and additives at least partiallyembedded into the host material and localized within an embedding regionof the host material, wherein a thickness of the embedding region is nogreater than 50% of an overall thickness of the host material.
 34. Thedevice of claim 33, wherein the thickness of the embedding region is nogreater than 40% of the overall thickness of the host material.
 35. Thedevice of claim 34, wherein the thickness of the embedding region is nogreater than 30% of the overall thickness of the host material.
 36. Thedevice of claim 33, wherein the additives are at least one ofelectrically conductive, semiconducting, photoluminescent, andmultichromic.
 37. The device of claim 33, wherein the additives includeat least one of a nanotube, a nanowire, and a nanoparticle.
 38. Thedevice of claim 33, wherein the additives include a phosphor.
 39. Thedevice of claim 33, wherein the host material has a first surfaceadjacent to the first cover and an opposing, second surface adjacent tothe second cover, and the additives are localized within the embeddingregion that is adjacent to the first surface of the host material. 40.The device of claim 39, wherein the additives and the embedding regioncorrespond to first additives and a first embedding region of the hostmaterial, respectively, and the interlayer further includes secondadditives at least partially embedded into the host material andlocalized within a second embedding region of the host material.
 41. Thedevice of claim 40, wherein the first embedding region is spaced apartfrom the second embedding region.
 42. The device of claim 41, whereinthe second embedding region is adjacent to the second surface of thehost material.
 43. The device of claim 33, wherein the additives are atleast one of patterned and unpatterned, and the device is a touchsensor.
 44. A device component with surface-embedded additives,comprising: an encapsulant including: a host material; and additives atleast partially embedded into the host material and localized within anembedding region of the host material, wherein a thickness of theembedding region is no greater than 50% of an overall thickness of thehost material.